I need some help. Just purchased a 1999 2.5L Sebring was showing a multiple misfire code but was running Ok. The spark plug tube seals were leaking so I replaced the valve cover seals, gaskets, plugs & wires, cap & rotor, and pcv valve. I ran half a can of Seafoam through the vacuum lines and the other half in the tank.
After doing this work, the misfire code went away and now it is running bad. Idle is a little shaky plus hesitating & sluggish when I hit the gas and shaking a bit. it smooths out at higher rpm's. It is throwing no codes. The condition goes from bad to worse to where sometimes you really have to mash the pedal to get it to run.
When I first had it back to together I reversed the manifold and egr vac lines coming from the solenoid and it ran really crappy. This was corrected and but now it just runs bad. It may be possible that the egr solenoid was damaged by being reversed but this seems unlikely to me.
I have checked all the vacuum lines plus did a leak check with starting fluid and propane. Did a visual inspection of the egr valve and associated plumbing, they aren't clogged. Connected vacuum to the egr, it opens and closes. Did a vacuum/electrical test on the map sensor and it is sending signal.
Did a fuel pressure test, had to make my own rig, it stayed steady at about 50 psi when revved.
The spark plug wires are in the correct order and an old plug was used to check spark, the spark will jump half an inch to ground. The new plugs do not look fouled.
I did a temperature check on the catalytic converter and it was reading about 290F on the intake side and 420F on the exhaust side. I also took out the O2 sensor just to make sure but no improvement in performance.
I also did a test for exhaust gasses in the coolant, there were no gasses.
The car sometimes shakes at idle but holds steady at 600-800 rpm. When it is revved in park it does OK but under load it hesitates but no backfiring or valve flutter.
My friend owned the car and changed the oil regularly.
It has high miles 258k, here is the result from a dry compression test: (1-6) 187,181,178,173,184,178
I think this compression is good for a high mileage car so it seems to me that the problem isn't the engine.

Any suggestions appreciated, thanks, Jim.

 

It is quite possible that the EGR valve was going bad before the seafoam, and it 'cleaned' it to the point that it started leaking...
The 'plug' portion of the valve 'disintegrated' on my 97 and it displayed behavior like you describe... but ALOT worse, to the point where it died at idle. Yours may not be that bad... yet.

Have the plugs been changed after this?

A thought!

 

The plugs were changed 4 days ago, the incorrectly installed egr initially carbon fouled the plugs so I had to clean them with a brush, what a pain. Once I corrected the egr, it has fouled them again.
I appreciate your input, will take another look at the egr. Perhaps I can put in a blocking plate on the exhaust tube where it meets the plenum and see if that changes performance.

Thanks, Jim