Chrysler Repair: 97 2,5L V-6 with P0300 and severe misfire at times, engine vacuum, air gap

Question
Vehicle is a 97 Sebring Convertible. Engine ran terrible at idle and had a code 303. I sprayed some carb cleaner around the intake and it surged. Pulled lower intake and found blown paper gasket at intake port #3. Installed a fel-pro metal gasket and new plugs,wires, and dist cap. Also repaired egr tube gasket at intake. Now it runs terrible off idle but idles well. Severe misfire and can only be driven while "feathering" the throttle. However if I really "hammer" it it does run well at high rpm. Same if I feather it. Brakes fine and vaccum does not seem to be a problem. Vehicle is almost non driveable as it just coughs and bucks when using throttle as designed. I made the mistake of being confident after the spray test and did not test drive before opening this car up. Present trouble codes other than the p0300 are random specific cylinder misfire codes. I have seen 302,305,306 flagged after resets along with the p0300. I did pull up wires on 2,4,6 to make sure the clips weren't pulled up. All was good. Please help!  

Answer
Hi Steven,
Thanks for the complete description. The troubleshoot for the 0300 is unfortunately very non-specific. Here is an answer I gave previously:

"The Chrysler troubleshooting manual lists the possible causes as:
secondary ignition wires, puel pump or fuel filter, injector harness connectors, ignition coil circuit, spark plugs, mechanical engine problem, contaminated fuel, water in fuel, PCM grounds, Injectors, Restricted exhaust, intake restriction, PCM, evap system, EGR system, Air gap at high rpm's, damaged sensor trigger wheel. That is quite a list!
The approach suggested is to check all electrical connectors and wiring, then do the tests in the following order:
secondary ignition
fuel delivery
engine vacuum
PCM power and ground connections
engine mechanical
The first one uses an engine analyzer scope to look at the high voltage pattern, then spray water on the cables to see if it changes. The possible repairs: individual spark plugs, coil or cable replacement
The second one involves pressure measurement and from there a variety of possible solutions
The third involves reading the intake manifold vacuum to see if it is steady at between 13 and 22 inches of HG. and if not the suspects depend upon the pattern shown by the gauge.
The PCM involves checking various wires at the PCM plugs
The last involves engine compression testing and a variety of other mechanical checks.
So I guess that beginning with the ignition wires makes sense unless you have a scope and the experience/knowledge at interpreting the patterns. You might try looking at the wires in the dark with the engine idling, then also spray some water mist on them to see in either case if you see arcing which would be a sign that the wires' insulation is breaking down. Then measure the coil resistances. If it passes that, then focus on the fuel filter and pump."

Recently, Kevin, the other expert in this category responded to a similar situation that you have described with a reference to a technical service bulletin:
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

So those are the best ideas I can offer. Please let me know what works for you.

Roland