I don't know what's going on but my turbo II is acting very strange. I recently rebuilt the engine and haven't put any miles on the engine but i let it get up to temp a few times.
I was working on my car this morning checking any and all things before i got ready to start it and check for issues. the car doesnt have any emissions equipment and it has a turbonetics t4 pretty small turbo generally speaking.

I had my car running very smooth, it started up completely fine and had a consistent 900 rpm idle. afr's were right around 10-11 (rich i know) but it wasn't showing any negative signs. while it sound and felt fine the vacuum didn't seem to be reading correctly cause it was 0.8inhg. after a little while i decide to let the car cool down and i'd put a seat in it and do some other minor things. when i went to start it up after working the car started up fine but the idle immediately started revving itself up to 2000 then coming down, then reving up to 2000 then back down. I shut the car off worrying that the something bad could happen to the engine. I wasn't positive but i thought i may have heard a backfire when it cranked up.

Is this an issue that anybodys seen frequently. i don't possibly see how i could have a vacuum leak cause i inspected every last intake part before working on it this morning
does this ring any bells.

 

you'd be surprised. never underestimate the sneakiness of vacuum leaks.

the next thing after that would maybe be to check the TPS. do you have a copy of the FSM? if not, you can get one at Foxed.ca

take a look here as well: https://www.rx7club.com/search.php?searchid=16876490