Hey gang. I’ve perused past threads and haven’t found one with my exact issue, though I’m betting it’s similar. Not sure this is specific to SRT-6, so putting in this forum. Here goes...

For some time, I’ve had an intermittent problem whereby the car (2005 SR-6, stock other than K&N air filter, 140K miles) misfires at WOT, or near WOT. If I pull over and **** it down, then restart, it’s usually fine.

About 6 weeks ago when temps here in MD were pushing 105°+, I started it and it was misfiring to the point of being undrivable. The first time it did it, I let it sit for 5 minutes and it started and drove fine. A few days later it did the same thing, on a very hot day, it did the same thing, but refused to run even after sitting. The next morning, when it was cooler it started and ran fine, so I moved it from the street to a parking lot. That after noon (after being I the hot sun all day), it did the same severe misfire.

It did the same thing for three days and I finally called AAA to tow it to the shop. Of course, when the truck arrived the ambient temp was lower and it started and ran fine.

During all of this, it never threw a check engine code, and since it didn’t have a code, the garage didn’t know what to do with it. I had a fuel filter and pump I had recent bought, but hadn’t installed, so I had them do that. Once done, they drove it and it did the same WOT misfire and threw codes (they did not tell me which), but after some apparent head scratching said it was “definitively” the ECU relay.

As you you might have guessed, not more than a quarter mile from the shop, I stomped it and it immediately misfired and threw codes. I had to order a new code reader (note to self: never leave your code reader in the car when you take it to a shop), so while I awaited delivery, I swapped the coils packs. I thought I made progress because after installing them, the CEL went out. But alas on a test drive, it did the same misfire.

The codes it is throwing are P0300, P0302, P0303, P0304, P0305, P0306. It has also thrown P0410 (secondary air injection), but not lately.

Testing driving it, I can rev it to redline by accelerating evenly with no issues. When the misfires occur is when I stomp it or downshift to a high rpm, as if it doesn’t like sudden jolts in revs.

As a bit of background, in adddition to the recent fuel filter, pump, EXU relay and coil packs, the crankshaft sensor was replaced about 20K ago and full tuneup with new plugs about 20K ago.

I have not pulled any plugs, but they don’t feel like the problem.

I’ve heard others have issues with the coolant temp sensor, or could it be the MAP? I could imagine the super hot temp issue being different than the WOT issue, but it feels too coincidental.