88 dodge shadow idles very ruff. pedal to floor to start.

Bury it.

P0300 Dodge P0300 Dodge - Cylinder Misfire Fault Detected Random Cylinders Possible causes
- Faulty spark plug (s)
- Faulty ignition coil (s)
- Clogged or faulty fuel injector (s)
- Intake air leak
- Fuel injectors harness is open or shorted
- Fuel Injectors circuit poor electrical connection
- Ignition coils harness is open or shorted
- Ignition coils circuit poor electrical connection
- Insufficient cylinders compression
- Incorrect fuel pressure

Start by checking for vacuum leaks, compression then a scan for fault codes. One of those should turn up a problem

I would check the timing could have jumped a tooth on the timing belt/chain. Also check the rotor in the distributer make sure that it is not worn out. I have also seen a plugged catletic converter cause big time power loss and really strange problems

What about the coil packs? Do you have a check engine light on? If so take it to an auto parts store and see if they will scan your vehicle for the codes.

my truck starts right up if I hold the petal to the floor but wont start if I don't hold petal to floor

What faults codes are showing on a test of the electronic engine control module?

I had an 88 that did something like that, it would idle up and down it seemed to be worse when the engine was cold. It turned out to be the MAP sensor, I never did get a check engine light. A friend of mine had the same truck and we swaped sensors back and forth until we found the problem.

fuel filter

you may want to check your injectors.