[Dream240]

I have a somewhat similar problem. Mine started right after my 5-speed swap.
I have an idle jump from 800 all the way to 1500, it's steady there for about 2 seconds, then it gradually falls back to 800 then it's fine.

This problem occurs when slowing down but, not until until I reach an absolute stop. Then bam idle jumps to 1500 rpms. I'm lost!!!

It also always happens the instant I touch the gas from a stand still. No matter what gear I'm in, even reverse and neutral. I initally thought it could be due to the auto ECU I still have. I'm thinking the ECU is trying to compensate for the auto downshifting into 1st at a standstill like when it was an auto tranny. Maybe the ECU is confused because I unplugged all those tranny connectors except the one for the speed sensor and back-up lights. Oh I also removed the Auto ECU under the dash (little green box).

My other guess is the AIV. I'm gonna check that tonight. I'm wondering if the fact that this car sat for 6 months has anything to do with this. I only did an oil change, and put in a new Cat with the new cat-back exhaust before my first 5-speed start up. Strange.

Sorry for the threadjack. Maybe we can both get some answers.