I have 1999 Toyota Tacoma Prerunner

V6 with automatic transmission

125,000 miles

Description of issue:

Truck randomly stutters at idle while in gear at operating temp.

After the truck is to full operating temperature, it will start to stutter randomly at idle while in gear. It is small stutter sometime once and then sometimes multiple times in a row. I notice this after leaving my house and coming to a stop light 4 miles down the road. To keep it from doing it, I will put the truck in neutral or just turn on the A/C to full blast to get the RPMs higher. The truck seems to idle at about 650 rpms when in gear and warmed up and do a sudden drop (stutter). Then recover quickly. The drop is never more than like 100 RPMs.

It seems turning on the A/C or putting it in park or neutral brings the RPMs up closer to 750 to 1000.

I recently changed all the spark plugs, wires, and coil packs because I had several codes come on for misfires. When replacing my spark plugs I noticed all were dry expect for one had oil on it. This would be the passenger side closest to the firewall.

Because of the stutter, I did pull and clean the throttle body and replaced the Idle air control valve and changed my air filter. None of these made the stutter better. Then I replaced the MAF sensor. Still stuttering. The stutters did start small and over the last 6 months they are getting more noticeable. More aggressive I should say.

I don’t know how old the fuel injectors are but I did add some fuel injector cleaner to my gas for a treatment and I don’t know if the stutter coincidently got worse or I was just paying closer attention to it.