Car "jerks" at wide open throttle at 40mph and 65mph Has new trans/tuneup/coil/air mod/

a 35year old car. never seen one me with less than 10 problems.
100% expected. USA car in OK state clearly told and nice!
NO ENGINE TOLD (size) car is called N13 you generation car.
auto tranny and with 4wd?
USA PULSAR NX, IS 1.6L DOHC OR SOHC ENGINE.
ALL ARE INTERFERENCE ENGINES,
NEVER IGNORE THE TIMING BELT . REPLACE IT FIRST.
so is and engine problem, not transmission failure to up shift, correct>? this fact must be learned first. or off base tests go.
engine Power loss has 50 causes. (electric or pure mechanical)
but in basic engine theory (ASE) and gas engines, and otto cycle engines,
the ordered list is.
1: good engine. . EGR not stuck open. CAM BENT NOT BAD OR WORSE SLIPPING. << FAST DRIVING THIS WILL Bring destruction.
2: good spark ,cap, rotor , HV spark wire set and plugs.
when 40mph cliff of failure hits, is engine misfiring? violently?
or is power loss smooth loss of power, RPM fails to rise more. but falls.
the former is spark bad. (ckp ,cmp or caused by cam belt slip)
#3 fueL
if slow smooth power loss,fuel pressure may be low.
if slow gee? the belt on the cam slips. never drive like that.
day one traded to this car, the belt is first ( I just hate bent valves)

Since you didn't provide a year and model, I can only generalize. Make sure the buttery-fly valve is moving freely and not binding, then check the idle air control valve, if the idle air control valve is stuck open, the car can actually drive upwards of 40mph without stepping on the gas.

If you need further help, reach me via phone at https://www.6ya.com/expert/daniel_4061c3d97c12c4c7

motor is worn

if your fuel pump is not bad ck the pressure , not sure of it but around 50 lbs I thing , ck the intake sometime the 4 bolts get loose and this will let to much air in and will not run right ,

are the A/C fuses good? what transmission, auto or stick?
the first check is , does the compressor, cultch, engage
and spin the actual compressor main shaft at full speed.
yes, then loop is bad. (freon loop) (fan good)
No, then below is wrong. (electrical)
94/metro/swift
did you check pressures yet?
if not , then the hi/low limit switch may be open killing the compressor
so it dont self destruct, never bypass this limit switch.
the High low switch if open kills DC power to the A/C main relay. coil.
coil yellow wire must be at 12vdc or the loop has wrong pressures.!
dig,. it refuses to destroy its self. so kills the relay.

all posts, USA.
does the A/C lamp on dash turn on? if not the blower is dead.!
on the 94,(i dont have 93 drawings)
you can get better drawings for 94 at alldata.com, any time.
yellow wire is hot. (clutch dead)


the next point of failure is the car has throttle pedal switch
that is closed all time but wot, wide open throttle cuts AC.
so this switch can fail and cut A/c (USE A VOLTMETER) opens.
the clutch has its own relay, that is controlled by
the A/C amp module (better name A/C logic module)
it cuts A/C for many reasons.
we use a voltmeter at the AMP mod..

inputs that can stop A/C compressor, are:
1: engine overheat sensor bad. 0v , goes to 12v at 235F engine temp.
pin 9.
2: pin11, not 12v means dash lamp out
3: pin 5, transmission cut, or throttle pedal cut out (WOT).
4: pin 4 and 10 , evap core iced up cut, thermister sensor.
5: pin 8, lost 12vdc power.

The TCM cut out , to pin 5 is just for automatic trans, with TCM shifter electronics, it sends cut when the trans detects overload.
(hills? or tranny goes to limphome mode, {sick})
see amp below.
that is it, for electrics. answer my first questions for better answers.

wheather your a2 .0 or 2.5 at idle key on engine off its is 0.7V to 1.1 V. you test it by doing a sweep, with your volt meter,voltage should increase with smooth throttle movement there should be no drop out or glitches and at wide open throttle you should reach 4.5 V , (***) wide open throttle

Check the WOT sensor. WOT = Wide open throttle.

there is a problem with the timing chain tensioner on these models, which causes poor driveability, normally the engine management lamp would be illuminated too

Start car and use a squirt bottle of water to wet the wires and coil, if you see it spark or run rough one or both are bad, repair the wires first as they are more common.

Fuel filter, air filter , timing, faulty wires, plugs, vacuum leaks, egr, low compression, brakes binding,, tranny fluid low,... start checking!