Ok I know there are other threads on this problem but nobody seems to come back with the final solution for their vehicle so I am asking for help with mine.
Mine is a 99 4Runner SR5 3.4 V6 with approx 140000. Got it 6 months ago and service records show the timing belt/water pump service was done at approx 109000. When I got it I did an oil change, seafoam in all 3 places, fuel filter, cleaned the MAF and throttle body, replaced the air filter and got new tires. Was running fine with the exception of a slight squealing when cold but that would go away as it warmed up.
Fast forward to last week. Only drove around 2000 miles since the above things were done. It was fine first thing when it was cold, idle was good no lights. After driving around then stopping for a short period of time then starting it back up and driving, it had a rough idle in park and when stopped. At normal speeds it wasn't rough but power slightly low. On the freeway at speeds over about 80 the check engine light would flash only. Slow down and the CEL stopped. Stop and the idle was rough. Took it home and thought maybe a clogged injector causing a misfire. Seafoam again through the plenum and in the gas tank. Then pulled the EFI fuse and the negative cable on the battery to reset. Drove it around and it ran like a champ. Started right up, no rough idle and no CEL at any speed on freeway. Stopped, turned it off let it set for a couple minutes then started it up. No issues at all. Idle was good. Drove it home on the freeway with no lights no issues so I thought problem solved. Went back out about 2 hrs later to run an errand and the same issues, rough idle, low power and CEL at speeds over 80.
In California you cant get codes read at auto parts stores so I decided to take it to an AAMCO I trusted and get the codes read and a diagnostic. I gave them the same details as above. They called later and said the tech drove around with a scanner on and got codes for a misfire in 2, 3 and 5. Tech recommended replacing two coils and the wires as they are original to the tune of $520. I asked (knowing the answer) if there was a way to troubleshoot without replacing the coils as I thought it was weird they would both go bad at the same time. He said not really they had to start somewhere and that was what the tech recommended. I was disappointed with this answer and said I would pick it up later as I didn't want to throw $520 at the problem hoping that fixes it.
I will get the codes when I pick it up but was hoping for guidance and/or advice from the forum on how I should proceed from here. I feel fairly confident with most do it yourself mechanical stuff on cars and I need to get this running at some point. I'm not made of money though so I can't waste it on hoping to find a solution.
Thanks in advance and I hope I provided enough details.
Mine is a 99 4Runner SR5 3.4 V6 with approx 140000. Got it 6 months ago and service records show the timing belt/water pump service was done at approx 109000. When I got it I did an oil change, seafoam in all 3 places, fuel filter, cleaned the MAF and throttle body, replaced the air filter and got new tires. Was running fine with the exception of a slight squealing when cold but that would go away as it warmed up.
Fast forward to last week. Only drove around 2000 miles since the above things were done. It was fine first thing when it was cold, idle was good no lights. After driving around then stopping for a short period of time then starting it back up and driving, it had a rough idle in park and when stopped. At normal speeds it wasn't rough but power slightly low. On the freeway at speeds over about 80 the check engine light would flash only. Slow down and the CEL stopped. Stop and the idle was rough. Took it home and thought maybe a clogged injector causing a misfire. Seafoam again through the plenum and in the gas tank. Then pulled the EFI fuse and the negative cable on the battery to reset. Drove it around and it ran like a champ. Started right up, no rough idle and no CEL at any speed on freeway. Stopped, turned it off let it set for a couple minutes then started it up. No issues at all. Idle was good. Drove it home on the freeway with no lights no issues so I thought problem solved. Went back out about 2 hrs later to run an errand and the same issues, rough idle, low power and CEL at speeds over 80.
In California you cant get codes read at auto parts stores so I decided to take it to an AAMCO I trusted and get the codes read and a diagnostic. I gave them the same details as above. They called later and said the tech drove around with a scanner on and got codes for a misfire in 2, 3 and 5. Tech recommended replacing two coils and the wires as they are original to the tune of $520. I asked (knowing the answer) if there was a way to troubleshoot without replacing the coils as I thought it was weird they would both go bad at the same time. He said not really they had to start somewhere and that was what the tech recommended. I was disappointed with this answer and said I would pick it up later as I didn't want to throw $520 at the problem hoping that fixes it.
I will get the codes when I pick it up but was hoping for guidance and/or advice from the forum on how I should proceed from here. I feel fairly confident with most do it yourself mechanical stuff on cars and I need to get this running at some point. I'm not made of money though so I can't waste it on hoping to find a solution.
Thanks in advance and I hope I provided enough details.
