Suddenly cranks over slowly like going to die. I know muffler bad too. Also beeps 4 times right when I get key in.?

no engine told at all, and is an engine/efi question. pure.
backfires to air clear or to rear tail pipe or muffler explosion.???
we can no hear it back fire and matters huge.
if only muffler explosion that is super rich fueling.
right fast foot can not save the stall right or even gets you full engine power doing so???????
your gm car has vin code and 8th digit is engine code
best is know what's under the hood first to fix any car.or truck
otherwise answers will be wrong,
a real shop opens the hood and goes AHHHHH
me zero. ahhhh
Avalanche 1500 or 2500?????????????????
good no Diesels here. (USA answers me)
5.3 L LM7 V8 (gasoline)
5.3 L L59 V8 (gasoline/E85)
8.1 L L18 V8 (gasoline)

we can not guess service history of any car /engines
21 year old spark plugs? no way are those good if true.
no miles on truck told. 250,000 miles? more?
got bad fuel, truck ran last month ok or last decade ok? history matters on all machines. for sure.
check all fuses yet, as in ALL
scan the PCM for errors called DTC and it shows p0300 ?
or other DTC errors. all modern cars are scanned first.
or go broke guessing you will.
bad spark the 5.3 runs 8 cops, but are not WELL cops they are hv wired cops.(packs) the 8 HV wires sets are never good at 21years later. they fail, hard.
as see here.
https://www.rockauto.com/en/catalog/chevrolet,2002,avalanche+1500,5.3l+v8,1377244,ignition,spark+plug+wire,7224


there are lots of causes under page 1 basics rules
bad engine,
bad spark
bad fueling.
compression bad. below 150 PSI or 0psi.oops. bad engines do not burn or make full power. even vacuums test bounce, no good that.
then spark we test spark on all 8 plugs( using tools for all tests)
last is fueling , good fuel,? , fuel pressure at spec,cranking and idling.
fuel pressure reg tests pass FPR.
this 5.3 runs a TBW system , throttle by wire if DTC error for it show up it will never ever run right .

there are 50 causes and up to 20 tests using tools to find them all
gue$$ing is not going to be cheap or worse. adding bad parts over good. oops. now 2 hard failures.

so what is the plan? nobody ever says hear.
buy tools and do the tests
?
or just want blind men to guess 50 times.
or get it service in a real show with real tools and skills.

now my silly guess
valve spring 1 cracked and valve sucked, and compression dead here#1. and vacuum nasty bounce ,PCM goes mad with nasty vacuum. it sure will go crazy. EFI just hates bad vacuum. MAP sensor goes nuts and sends nuts readings to PCM, and PCM is clueless what to do. for a fact. ( it will try and fail hard)

1 of 50;

fuel pump
,It could be a weak, faulty fuel pump, try this next time no start happens, try key on and off 5 times, without starting and wait 10 seconds between cycles. This sometimes brings the fuel pump prime up to pressure and engine will start.
press the helpful button

why replace very expensive parts, guessing.?
so runs ok , dies runs ok, dies, ? is that it? hot, and cold?
did you do the 60k tune up yet, this repeats ever 60k miles.
that be first.
then see if you can save the STALL , with a fast right foot action.
yes, and has full power up any hill at that time, its not the fuel pump.
stalls have 4 major causes and 4 tests..
you can do the tests. or spend a fortune guessing, its your car and your bread (cash).
one very common cause is the EGR sticking open , the main EGR valve.
other:
1: 12vdc lost to the EFI system, the dash goes dead. lost elect. power.
2: lost compression , can happen hot engine only.
3: bad spark.
4: bad fueling.
there are simple tools and simple tests for each
do you want to test, or gue$$?

(EGR sticking or iSC sticking both can be clean before spending big cash guessing parts)

the fast foot answer, is the KEY FACTORY answer that
1 question and 1/2 the work stops. ive posted this many times.
and not one answer,
car starts to stall?
i slam right foot to floor.
engine, dies, or
is easy to save stall
or hard,
if i can save it , I IMMEDIATELY check for full engine power.
go that?

I think you were on the right track with the key lock and ignition switch. It sounds like the lock is not turning the switch far enough.
There are gears between the lock cylinder and switch that may not be aligned up right.
The anti-theft system would prevent the engine from cranking, but the security light should be flashing if the system thinks the truck is being stolen.

Hello Donn,

UN-fortunately 1988 is WELL before the OBD
(on board diagnostic)... DIAGNOSTIC TROUBLE
Codes (DTC) got standardized...

So DAYS can be wasted looking for commonality...
(troubles).

Rather than assuming your spark, timing, fuel, ECU...
Oxygen Sensors. INJECTORS are all askew...

I would suggest that if you SATURATED YOUR
HEADER BOLTS with LIQUID WRENCH...

and opened you EXHAUST ahead of your catalytic
converters... ahead of your mufflers... you engine would run...

Obviously DANGEROUS to operate in that condition... at
least you would know what had to be REPLACED before
you can operate your vehicle SAFELY.

If you decide the job is a bit too much... at least
check out your PURCHASE cost of a replacement
CAT and/or MUFFLER...

Try rockauto
http://www.rockauto.com/en/catalog/ford,1988,f-350,7.5l+460cid+v8,1126437,exhaust+&+emission

1988 FORD 350 7 5L 460cid V8 Catalytic Converter RockAuto

1988 FORD 350 7 5L 460cid V8 Muffler RockAuto

Bad crank sensor will cause your jeep to stall out while driving then start right back up after cooling off a while. It's going bad slowly but surely.

first i try unpluging the the electric connector on the transmission cause if it stahls in gear ur torque convertor might be lock may be check the throttle poition sensor / and ur egr tube 4 the rpm probs let me know if that changes anything

2 possibilities
* crank sensor
*catalytic converter plugged

I would replace the dle Air Control solenoid. I know its a guess, but its a common thing. when cranking the engine, the idle should flare high, and then slowly down to idle speed.

Most often that is a symptom of a fuel pump beginning to fail. As it runs, it begins to overheat and bind. After it cools down, it frees itself up and then works again. However, the same problem can also be caused by a crank position sensor going bad.
Next time it happens, turn the key on while someone listens to hear if the pump (inside the tank) is running. If not, likely that's what is failing.
Crank sensor can be tested with a digital ohmmeter, but many times it will not show up as bad until it completely fails.