I have a 2004 Sequoia that started sputtering while driving. It tripped the CEL and I took it to Autozone and had them read the code. Turns out one of the coils was bad. Replaced it and everything worked great for about three weeks.

However, engine is sputtering again while driving, but it isn't tripping the CEL. When I had them re-read the computer, it came up clean.

I did not replace the sparkplug when I replaced the coil pack. Could that be an issue, and wouldn't it trip the CEL?

Someone suggested running seafoam through to clean the injectors. Have done two tanks and still no improvement.

Any ideas?

 

When were spark plugs last replaced? Those are copper and recommended every 30k miles .

Sometimes I see a few coils go out within short period of time from each other on the 2UZ V8. Without a misfire code it's a little harder to diagnose.

The best thing to do would be to use a scan tool to watch the ECU misfire data while it's sputtering, showing which cylinder is misfiring. I do not know if Autozone can help with that or not.