Replaced cam sensor,oxygen sensor, egr vavle, when normal operating temp vehicle dies at stop signs and has jerking and sputtering when accelerating

OBD II Fault Code

• OBD II P0402

Fault Code Definition

• Excessive EGR Flow

Symptoms

• Check Engine Light will illuminate
• In most cases, there are no adverse conditions noticed by the driver
• In some cases, there may be performance problems, such as dying at stop signs or rough idling, hesitation, misfires or lack of power (especially during acceleration), and a decrease in fuel economy

Common Problems That Trigger the P0402 Code

• Excessive Vacuum signal or Electrical signal to the EGR Valve
• The EGR Valve is defective and is opening too far or not properly closing
• Lack of proper EGR system feedback to the computer from the:
  
  • Manifold Absolute Pressure Sensor (MAP)
  • EGR Temperature Sensor

Common Misdiagnoses

• Ignition System
• Fuel System
• Oxygen Sensor
• EGR Valve

Depending on what engine you have, I know the 1.6 DOHC engine has the cam sensor right at the top front of the motor. You must make sure you have your timing belt serviced at the suggested intervals or you will have a large repair that you can't afford. The recommended service interval is 72,000 miles. If you do not have your belt changed at the service interval it will cost you upwards of 1,200 bucks to have it fixed after the valves are bent and need replacing.

sounds like you are not getting any oxygen into your motor or you may have a bad Oxygen Sensor or maybe even a bad Catalytic Converter. I would also check my MAP and my Air Intake Control sensors

Change the coolant temp sensor,and possibly the EGR position sensor.

dirty throttle body, check air filter.

Here is a code list for you. Remember this doesn't always mena a sensor issue, the problem can be in the wiring as well, or in the case of a lean code you may have an actual lean condition due to a vacuum leak at the intake or vacuum hoses or connections. I have highlighted your fault codes and added extra notes.
GM common codes for OBD1 (for vehicles made before 1995)
12 System normal
13 oxygen sensor circuit open
14 coolant sensor high resistance or shorted
15 coolant sensor circuit low or open
16 direct ignition system (DIS) fault in circuit
17 cam position sensor fault
18 crank or cam sensor error
19 crank sensor circuit fault
21 tps sensor out of range
22 tps sensor signal voltage low
23 intake air temp sensor out of range, low
24 vehicle speed (vss) sensor circuit fault
25 air temp sensor sensor out of range, high
26 quad-driver module (computer) circuit #1 fault
27 quad-driver module (computer) 2nd gear circuit
28 quad-driver module (computer) circuit #2 fault
29 quad driver module (computer) 4th gear circuit
31 camshaft position sensor fault
32 egr circuit fault
33 map sensor signal out of range, high
34 map sensor signal out of range, low
35 idle air control sensor circuit fault
36 ignition system circuit error
38 brake input circuit fault
39 clutch input circuit fault
41 cam sensor circuit fault, igntion control circuit fault
42 electronic spark timing (EST) circuit grounded
43 knock sensor malfunction or electronic spark control (ESC) circuit fault (ignore this for now)
44 oxygen sensor lean exhaust (make sure you no engine vacuum leaks)
45 oxygen sensor rich exhaust
46 pass-key II circuit or ps.pressure switch circuit fault
47 pcm-bcm data circuit
48 misfire diagnosis
51 calibration error, mem-cal, ecm or eeprom failure
52 engine oil temperature circuit, low temperature indicated
53 battery voltage error or egr or pass-key II circuit
54 egr system failure or fuel pump circuit low voltage
55 a/d converter error or pcm not grounded or lean fuel or frounded reference voltage
56 quad-driver module #2 circuit
57 boost control problem
58 vehicle anti-theft system fuel enable circuit
61 a/c system performance or degraded oxygen sensor signal
62 engine oil temperature high temperature indicated
63 oxygen sensor right side circuit open or map sensor out of range
64 oxygen sensor right side lean exhaust indicated
65 oxygen sensor right side rich exhaust indicated
66 a/c pressure sensor circuit low pressure
67 a/c pressure sensor circuit or a/c clutch circuit failure
68 a/c compressor relay circuit failure
69 a/c clutch circuit head pressure high
70 a/c refrigerant pressure circuit high
71 a/c evaporator temperature sensor circuit low
72 gear selector switch circuit
73 a/c evaporator temperature circuit high
75 digital egr #1 solenoid error
76 digital egr #2 solenoid error
77 digital egr #3 solenoid error
79 vehicle speed sensor (vss) circuit signal high
80 vehicle speed sensor (vss) circuit signal low
81 brake input circuit fault
82 ignition control (IC) 3X signal error
85 prom error
86 analog/digital ecm error
87 eeprom error
99 power management

This is code 12 and it means "System Normal"
Here is the complete list of fault codes for your Buick
GM common codes for OBD1 (for vehicles made before 1995)
12 System normal
13 oxygen sensor circuit open
14 coolant sensor high resistance or shorted
15 coolant sensor circuit low or open
16 direct ignition system (DIS) fault in circuit
17 cam position sensor fault
18 crank or cam sensor error
19 crank sensor circuit fault
21 tps sensor out of range
22 tps sensor signal voltage low
23 intake air temp sensor out of range, low
24 vehicle speed (vss) sensor circuit fault
25 air temp sensor sensor out of range, high
26 quad-driver module (computer) circuit #1 fault
27 quad-driver module (computer) 2nd gear circuit
28 quad-driver module (computer) circuit #2 fault
29 quad driver module (computer) 4th gear circuit
31 cam position sensor fault
32 egr circuit fault
33 map sensor signal out of range, high
34 map sensor signal out of range, low
35 idle air control sensor circuit fault
36 ignition system circuit error
38 brake input circuit fault
39 clutch input circuit fault
41 cam sensor circuit fault, igntion control circuit fault
42 electronic spark timing (EST) circuit grounded
43 knock sensor
or electronic spark control circuit fault
44 oxygen sensor lean exhaust
45 oxygen sensor rich exhaust
46 pass-key II circuit or ps.pressure switch circuit fault
47 pcm-bcm data circuit
48 misfire diagnosis
51 calibration error, mem-cal, ecm or eeprom failure
52 engine oil temperature circuit, low temperature indicated
53 battery voltage error or egr or pass-key II circuit
54 egr system failure or fuel pump circuit low voltage
55 a/d converter error or pcm not grounded or lean fuel or frounded reference voltage
56 quad-driver module #2 circuit
57 boost control problem
58 vehicle anti-theft system fuel enable circuit
61 a/c system performance or degraded oxygen sensor signal
62 engine oil temperature high temperature indicated
63 oxygen sensor right side circuit open or map sensor out of range
64 oxygen sensor right side lean exhaust indicated
65 oxygen sensor right side rich exhaust indicated
66 a/c pressure sensor circuit low pressure
67 a/c pressure sensor circuit or a/c clutch circuit failure
68 a/c compressor relay circuit failure
69 a/c clutch circuit head pressure high
70 a/c refrigerant pressure circuit high
71 a/c evaporator temperature sensor circuit low
72 gear selector switch circuit
73 a/c evaporator temperature circuit high
75 digital egr #1 solenoid error
76 digital egr #2 solenoid error
77 digital egr #3 solenoid error
79 vehicle speed sensor (vss) circuit signal high
80 vehicle speed sensor (vss) circuit signal low
81 brake input circuit fault
82 ignition control (IC) 3X signal error
85 prom error
86 analog/digital ecm error
87 eeprom error
99 power management

time to buy a new van.. umm what about the alternator?

When fixing codes start with first code first / it dos not always mean that the sensor is the fault ,it could be in the harness / the plug or the ground. and reference signal should be tested , but in this case you most likely could get away with replacing the cam sensor, that would be the Lest expensive and easiest to start with,to git to it you will have to remove the alternator hope this is help full, the other code suggest that it could be the crank sensor , that and the plug for it does fail quite often but first things first feel free to ask if you should have any further questions , Thank you ,

Trouble Code 33 and 34 are the MAF/MAP Sensor Circuit. It sounds like you've replaced that sensor already. Did you also have the code 34 before putting in the new sensor?
Or did this code start after it's replacement? Any other codes appearing?

Troubleshooting it would depend if it has the Speed Density Update. The dealer should be able to provide that info.

Here's your fault code list:

13 oxygen sensor circuit 14 coolant temp sensor circuit (high temp) 15 coolant temp sensor circuit (low temp) 21 throttle position sensor (TPS) circuit (high signal) 22 throttle position sensor (TPS) circuit (low signal) 23 manifold air temp (MAT) circuit (low temp) 24 vehicle speed sensor (VSS) circuit 25 manifold air temp (MAT) circuit (high signal) 31 wastegate solenoid electrical circuit 32 exhaust gas recirculation (EGR) circuit 33 mass air flow (MAF) circuit (gm/sec high) 34 mass air flow (MAF) circuit (gm/sec low) 41 cam sensor circuit 42 C3I EST or bypass circuit failure 43 electronic spark control (ESC) circuit 44 oxygen sensor circuit (lean exhaust) 45 oxygen sensor circuit (rich exhaust) 51 PROM error 52 calpak error 55 ECM error