Chrysler Repair: P0300 Random Misfire:2.5L V-6, chrysler sebring, muffler shop

Question
I've written back and forth with you about the issue with this code on my 1999 Chrysler Sebring 2.5L V6.

The history: My distributor went on my car about a month ago. We didn't know it was that at the time so we replaced the fuel pump, timing belt & water pump, then to come to the distributor being replaced. I had a faulty rebuilt fuel pump & a faulty rebuilt distributor. Both of those have been replaced. The car is running but I get P0300 random misfire when hitting driving speeds of 65-70 mph. The check engine light starts flashing, goes out and then flashes again and stays on and then intermittently will flash again and stay on.

We have taken off the EGR valve as you instructed and checked to make sure it opens and closes. It was a little sticky but my husband freed it up with WD-40 and cleaned the gasket and reinstalled it. Also new spark plugs were installed. New plug wires last year as well.

I still get the PO300 code so my husband was wondering if the timing belt tension pulley is not set correctly will that give you a random misfire? Or would a fuel filter (replaced last year) cause that or a catalytic converter?

I would assume if an O2 sensor was going, my DTC code reader would be able to detect that?

We're kinda running out of ideas. This code is a stumper for sure. Any ideas would be appreciated."


Answer
Hi Danni,
A fuel filter can cause a loss of power at high speeds, but it seems early for that to be bad again. A catalytic converter with a loose honeycomb inside can also clog up the exhaust pathway at high rpm and produce missing (listen for looseness/rattle from the converter or tap on it and listen/or have a muffler shop test it). I agree that the O2 sensor would set a code if that were the cause.
There is a procedure to set the tension of the timing belt using a miller tool #998767 and torque wrench which if that wasn't done properly could I would think result is cam timing problem probably most notable at high rpm. So review what was done when the timing belt was replaced.
Finally, Kevin had a questioner with the 0300 problem and came up with this Technical Service Bulletin about the egr:
NUMBER: 18-020-01
GROUP: Vehicle
Performance
DATE: Aug. 17, 2001
SUBJECT:
Rough Idle, Hard Start, Start & Stall
OVERVIEW:
This bulletin involves: Installing a revised EGR valve.
MODELS:
1995 - 2000 (JA) Breeze/Cirrus/Stratus
1996 - 2000 (JX) Sebring Convertible
NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 2.5L ENGINE.
SYMPTOM/CONDITION:
Vehicle may intermittently exhibit any of the following conditions:
• Rough engine idle.
• Hard start or long crank after hot soak.
• Start and stall when started with cold engine.
• Diagnostic Trouble Code (DTC) P0300, Multiple Cylinder Mis-fire.

04287646AC Valve, EGR

I can't give you any experiences about whether trying this revised egr works or not for this code.

Sorry to give you so many possibilities. Please let me know if you find out which is the answer for your engine.
Roland