I took advantage of spring break this week. Changed manual transmission fluid, rear differential, went to a muffler shop and had them put a flowmaster 50 series on my truck, and I did the ISR mod.

I have a 91 Toyota 3vze with 5spd. I used to idle (for many years before this week) at about 1100 RPMs, now after all those things I'm idling anywhere between 500-750 RPMs. Despite all these things happening in a relatively short time frame, I think the muffler is the main cause as I remember nearly killing my truck pulling out of the muffler shop, not use to the low idle. So me not knowing much about vehicles, I'm wondering if this is a bad thing.

 

Could be a lot of things... does it run smoothly at the lower rpm?

Btw, it is easy to adjust, although you are right to try and understand why it is idling low.

 

I just pulled it into the garage to adjust the idle, and it started idling low enough to kill it. Before this very moment though it ran fine at the lower idle. I'm going to adjust it back and hope it solves the problems.

 

1100 was too high - should be about 800

http://personal.utulsa.edu/~nathan-b...e/64tuneup.pdf

They may have adjusted it, and went too far.

 

It was a problem with the ISR mod, one of the clamps came lose. Too bad I didn't figure that out after spending half an hour messing with the idle. =/ Guess you live and learn. Thanks for the help.