Hi, I own an 03 Buick Park Avenue 3.8 NON-supercharged. It has a rough idle and stuttering at freeway speeds, Approx 1600-2600 RPM, most noticeable during torqe converter lockout, at approx 15-30% throttle. So far I have checked MAP, TPS, and Airflow sensor. When parked reving the engine (warmed up) to 1500RPM for about 3-5 seconds then quickly letting off will cause the engine to stall. Now I am getting a "service engine soon" light. I've never quite seen a case like this (with all my limited automotive experience, lol) and am stumped on what to check out next, besides codes.

Recent work I've done includes, Spark-plugs, wires, oil change.

53k miles

could be a coil, codes would help. does it do it worse the hotter it gets?

First, get that code read. Is the SES light flashing? I suspect a misfire. A bad coil, bad plug, or bad plug wire.

It'* the same hot or cold. Now that you mention the coil, I had a 95 grand am with a 3.2 (lemon 3trans and 2engines) that had the same issue, and it looks like it uses the exact same type of coil. Though I can't see any kind of arc burn on the outside plastic of the coil, like the other car. Although, that doesn't mean it can't be internal.

I'll be getting a Chilton book to read the codes in the next couple of days. I'll keep you guys updated. Anybody know the procedure for reading pins without a reader (pin jumping)?

SES light wasn't flashing, and now it has turned off. Although the rough idle / stuttering remains. The Plugs/wires, are 5 months old mid-grade wires and double-platinum plugs (non gap-able). Which were recommended on most of the forums I looked through before purchasing them.

Take a look at your rear plug wires. Are they near or touching the O2 sensor wires?

Let me know what you think

That one wire is a bit close. Have you pulled the plugs and inspected them? Another test you can try is take a spray bottle filled with water. Start the engine and mist the coils and plug wires, turn off the light and look for any blue flashes. If you see any then you have a short. This will cause problems.

I'll do the spray bottle test first, and let you know if that shows anything. Then, I'll pull the plugs after a few hours when the engine cools off, and let you know what I find.

Thanks for all the help so far.

Did the spray bottle test, and couldn't see anything. I'm headed out to dinner so I'll pull the plugs tomorrow, as I'm not going anywhere, I'll let you know what I see.

I can see how the wire being close to the Ox sensor would cause a false reading by induction, and then the computer would run rich or go into limp mode.