Idle Issue/Car Dies when let off gas
 

Hello everyone! Some back story: I have my friends 85 RX7 GSL in my garage right now. We picked the car up last year and since have put a lot of work into it. The previous owner created a wiring nightmare that has since all been repaired. Anyway last week I tore everything out and rewired the entire car along with repairing many other things. The car ran fine before the work, it has a full header back exhaust, Holley Red Fuel pump, Mikuni 44 Carb, Tapped for NOS wet shot, Two MSD 6AL, Holley FPR and a few other goodies. The Car ran with all of this just fine before we started (the Holley red was was leaking so this was replaced with a new one). Anyway earlier this week I got everything back together and faced an issue with the MSD wiring, that issue has since been fixed and both leading and trailing have proper spark, the fuel pressure gauge also shows fuel pressure to the carb. The car starts up but it doesn't want to idle. I will get it started, it runs rough and then if I let off the gas it dies. The carb wasn't touched when it was off the car other than cleaned. A new intake manifold gasket was installed and a used brake booster was installed due to another project. At this point after exhausting all other options I feel as if its a vaccum leak issue however I cannot seem to track it down. Any ideas? Possibly something with the carb? Any help would be greatly appreciated as I need this Car out of my garage by Friday.

A picture for reference if this helps.

Did you try plugging the vac line to the booster? Could be a leaky booster.

Looking at that picture I see no line for vac to the booster and nothing on the intake nipple
to plug that connection. I'm assuming this pic is before hooking that up, otherwise thats a huge
vac leak.

I can get an updated picture, but yes that was before final assembly. I will plugging the booster and see if that does anything. My other thought was possibly one of my four NOS taps in the manifold could be leaking.

i would play with the idle mixture, if the ignition changed that might have also

Here are some updated pictures, I checked the booster and it does not seem to be the issue.

Does anyone know where the idle adjustment is on the Mikuni?

Honestly I don't think the carb is the issue, everything was set perfect beforehand, I'm afraid if I start adjusting it now why the car is running like this it will only make things worse. I originally thought it was an ignition issue once you start driving the car runs great and I am getting spark as well as proper timing. How about fuel pressure would that cause issues at idle but not so much under load?

Can you turn the strut tower brace the other way, or was it designed backwards?

That's a good question, it came with the car and I left it in that orientation when I put it back on after painting.

Probably won't clear the alternator the other way.

Is it from an FC? never seen that one before...

I test fitted it the other way but the hood did not close, I got it with the car so I'm not sure of it origin. Just an update, the idle issue is fixed. I pulled off the manifold and found that it was warped, I got it level and a fresh gasket and now its running great.

thats the star mazda intake copy right?

The "copier" of those mani's has a warped mold, just fyi. I have seen a bunch already not flat towards the trailing edge on rotor 2's secondary port.

Yeah Star Mazda Rep, essentially exactly what haopened. It is running great now though and in the process I got a lot of other things taken care of.