Tried to start the engine and before it started, i heard a pop and felt the gas pedal come back to my foot. opened hood and the plastic engine cover was in pieces, anyone ever heard of this. it has

Almost sounds like maybe a motor mount issue.

Look underneath at where the pedal mounts, My bet is the plate that is mounted to the pedal has cracked. Im not saying you should, But i would leave it in place & spot weld it.

slave cylinder is my first suspect.

Are there threads on the sensor ? stripped where it screws into ? Have to have it fixed ,thread repair kit !

ok i have a 1998 durango with the 5.2L 318 engine. had trouble with a bad cell in my battery. I went out bought an optima red top battery for it 800cca. put it in and had same trouble. No start without putting foot on gas. wouldn't stay running without holding foot on gas. CPU has to relearn it's programming once you unplug it for long periods of time. mine was without power for about 2-3 weeks till i got new battery. Start with this.. first check under air filter make sure a squirrel hasn't made a mess under your air filter and it's clogging the air intake. Then pull off the lid to your injector cover ( the screw down lid coming from the air box ( with air filter in it) to "carb") make sure all your cables move freely. put that all back together and close hood. Start truck with foot slightly on gas pedal to get started. keep it at about 1k to 1500 rpm for about 1-2 minutes. Rev motor to about 2500rpm and let it die out if it will. Get out lock doors with key fob if you have it. if not make sure to lock doors. ( trust me it worked for me) let sit for 5 minutes. come back out and unlock door and relock door 3 times with fob ( if you have it ) or key if you don't have a fob. Then unlock it with the key and enter vehicle. Start truck as before and keep it around 1k to 1500 rpm again for about 30 seconds rev it up and should keep running. Mine did. I think the iac was stuck from sitting and has now since loosened up.
Good luck hope ti works for you.

This is pretty simple, pop your hood open and look on the left side
with the car is running turn the screw counter clock wise till your rpms reach the 1 mark you will find the screw located in the same metal bar as the foot pedal cable...still cant find it ? pop the hood open and tap the gas pedal till you see the pedal move the cable line to carburetor under your hood it is right above the alternator.

Sometimes the screw gets messed up and you will have to replace the whole screw and crew housing this happens when it sticks there is also a pin that is under the circle wheel part of the idler.

air lock maybe need to bleed it or remove filtre fill will clean diesol and refit and prime it

when you press the gas can you hear the engine accelerate if you can then that means it is your transmission if you cant it is your gas cable linkage just snap you can just replace it by removing your engine cover then add a small nut and tie it to the end of your gas linkage strech it in to the plastic arm and you can then use it to take to your mechanic to fix it properly

It sounds like the engine "backfired" and blew the cover off. This and having the tach "jumping" means that the engine timing is erratic. This can be caused by the crankshaft position sensor or the ignition module. It could also be cross firing at the coil pack,if so equipped. Make sure all of the wiring to these components is good.