Having some issues after top-swapping my '99 GT. Replaced the fuel filter, also.

Steady and constant misfire on cyl 3 at idle after running a few minutes - closed loop. When I give it gas, above 1500 rpm, the misfire goes away, but comes right back when I get off the gas. It's like #3 isn't firing at all at idle.

Blinking SES, but no code set. Yes, gas cap is tight.

Exhaust smells like raw fuel, but the car runs lean (O2s report, anyway). I assume this is due to no fire on 3, and the fuel is just dumping into the exhaust.

I swapped the injectors around, misfire stayed on #3. Swapped plugs, wires, coil packs, and new ICM (the stock one went bad sitting on the shelf during the swap, go figure), always misses on #3. Could this be a fuel pressure issue? I'm using the stock GT fuel pump.

If so, what pump is recommended, and where is a good place to get it?

Car runs fine otherwise, with less KR than when it was N/A.

One more thing I'm going to check is compression. Need to find some free time for that.

'99 L36 bottom
Ported Gen 3 with 3.8
L67 injectors
L67 bin
No EGR or BBV

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-David

No. This isn't a fueling issue. Not if it is on just one cylinder. I would suspect a cracked head, a bad connection at the crank or cam sensor, or a bad PCM.

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One Big Ass Mistake America

I would get a noid light and check the injector pulse at idle compared to the other cylinders.

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2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

Here's what the exhaust sounds like. When I unplug #3 (plug/injector/both), it sounds the same, when any other wires are pulled, it sounds rougher, so it's obviously on #3.

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-David