Chrysler Repair: P0300, P0301, P0303, & P0305 codes: 2,5L V-6, upper intake manifold, chrysler sebring

Question
Hello,

I keep getting the same codes on my 1999 Chrysler Sebring JXI 2.5L. P0300, P0301, P0303, P0305, and P0300 again. Replaced all spark plugs and wires, new distributor unit (including cap & rotor), and ignition coils and it's still having the same problem. I had a diagnostic test done and they said there was no problem with the EGR valve and that there was a problem with the distributor unit, which they replaced, but it didn't fix the problem. Also, because the misfires caused the check engine light to come on, it wouldn't pass the smog test. The mechanic I took it to replaced the distributor unit and said that it solved the problem and it passed the smog. But 1 week later, the same codes came up (after driving about 100 miles). How could it pass the smog while still having the same problem that was preventing it from passing in the first place?

Answer
Hi Allison,
Are you sure the old codes were erased? These could be stale.
Do you feel the 'miss' again? If so then the codes are real.
One questioner with a similar problem found that there were oil fumes entering the distributor because of a loose distributor shaft but that shouldn't be true with a new ditributor. But maybe the crankcase is pressurized by a faulty pcv valve, so check for that possibility.
Those 1,3,5 plug are on the back side of the engine and it requires removal of the upper intake manifold to get to them. It could be there is a slight manifold leak causing the missing. That could be tested by spraying very small spurts of starting fluid around the edge of the manifold gasket while the engine idling to listen for a change in the idle speed. Be very careful to just use small squirts due to the flammability of starter fluid.
I would go back to the mechanic who replaced the distributor and ask him to figure out why the problem has started again and mention some of my ideas. It should be covered under most warranty for labor/parts situations since it was so recent and probably so costly too.
Roland
Sorry for the delay but I just found your question in the 'pool'. Please 'rate' my answer and where you see the question about "volunteer or the month' please consider a 'yes answer if my response has been helpful. Thnaks