I have a 1990 RX-7 non-turbo. The damn engine light won't go off my uncle, the mechanic doesn't know how to find or fix it. The damn thing won't stop jumping up and down. It Idles at around 2000 rpms' when you first start it up then after about 5 seconds it jumps down to 1000 then back up to 2000 then back down to 1000....etc It does this EVERYTIME. I've talked to other RX-7 owners and theirs do it too, but not as extreme as mine. They told me its normal, but I don't like it. I'd like to fix it. Anyone know what the problem might be?

 

Throttle Position Sensor may need to be adjusted. Or you may have a vacuum leak somewhere. Pull the check engine codes and see what you get and go from there.

http://www.rx7city.com/ecucodes.htm

Go there for the codes.

For the TPS check out ReTeds homepage he has a good write up I believe. I think his site is http://www.f3cs-pro.com