Atrompke

Hello,
Im not very car savvy but my father has been helping me with this issue. I have a P0304 code showing up. Cylinder 4 misfire. It's a 99 Lexus ES300 with 81,000 miles on it . My dad replaced all of the spark plugs because he believed that that was generally the cause of the code. However, the car ran for 5 minutes and when I left his house the check engine light came back on. Since then I have been driving the car and it has been rough and shaking when it's idling and when there's no force on the accelerator. Also it seems to not shift downwards to a lower gear. For example when I get on the freeway, it goes from 20 to 60 very very slowly and never shifts down. It also seems to rev very high sometimes around 4500 RPM. There was one time when I was city driving and I couldn't get above 20 miles an hour no matter how hard I press the accelerator. That day, I put a fuel injector cleaner into the gas tank and while that has not happened again the check engine light and symptoms are still happening. I know I'm looking at a lot of options for this code failure and I'm not really looking forward to pay a mechanic that much. Does anyone have any suggestions to narrow it down given these symptoms? Thank you for any and all help!

Nad1370

Atrompke

Thank you! That was so helpful to know the order of the cylinders. My dad had said this was the only car he's ever seen with six coils. And no, we just assumed. But it's acting the same way. We'll retest it. This is probably a silly question that my dad probably already knows the answer to but is that 2-4-6 in the front or in the back? Thanks so much and I really appreciate your help!

Nad1370

It's the front one.
The accessible one.

The rear coil packs which is is under the intake plenum is
Cylinder 1--3--5