P0302 Jeep -

Question

I have a 2001 Jeep GC 4.78L with 213K + miles. We have replaced the fuel pump (pain in the butt), the Crankshaft Position Sensor and all 8 Spark Plugs. We are down to getting the P0302 code. The jeep starts fine from a cold start and runs good. It runs fine but will start to idle just a little rough as long as you don't shut it down. If you go to the store or someplace where it is shut down for a short period of time it is hard starting. Turn the keys, it turns over but don't start. This can be done several times until it does finally start but then it acts like it is only firing on a few cylinders. after a few moments it will finally gain a decent idle and run again.
I did notice that the fuel cap seal is cracked and my husband says that there is an inline fuel filter that we have not changed over just yet.
When my husband changed over the CPS, he said the old one broke while taking it out but everything came out and the new one went in just fine.
We have tried the fuel additives to clean the water from gas and to clean the injectors.
I am at my wits end but can't afford to take in to a dealer for diagnoses. Can you give me another area to look at with this problem.
Thanks, Mary Gerard