Pontiac Repair: 2000 sunfire hesitation, chevron techron fuel system, chevron techron fuel system cleaner

Question
I have a 2000 sunfire 2.2 and when i start it up it shakes for about a minute and then it seems to idle ok but when you push the gas there's a slight hesitation like it wants to stall but it catches. I let it run for a few minutes and then shut it off and it will not start again until it has sat for a long time. The engine light was on with codes and i replaced the cranshaft position sensor, fuel filter and spark plugs. After changing all that the engine light and codes are gone and it runs a little bit better but it's still hesitating and wont start after shut off. I do have a valve cover gasket leak and two of the plug wires were oil on them but not down in the spark plugs. I didn't change the plug wires. Any idea?

Answer
Hi Heather:

what happens to this when you say it will not start? is just crank over and will not start? doe it have to sit again untill it's cold before it will start? There can be a lot of issue that could cause a rough running issue cold. A coolant tempature sensor that is reading wrong can cause this type of an issue if that sensor is readin incorrect it throws off the fuel delivery. You could have an issue with a fuel injetor that is leaking and it's running real rich on a cold start. I would try a few bottle of Chevron Techron fuel system cleaner. follow the directions on the bottle. Does this run worse when it's damp and cold out? if so it could be a bad set of plug wires. oil leakin on them for a prolonged period of time breaks down the insulation on the wires and they could start to "leak" and cause a misfire due to the spark "leakin" past the insulation and not firing the spark plugs.
Good luck :)