When ever I press the brake, my lights dim a little. Also, my idles at 1000 RPM (finally above 200 RPM!!!) but as soon as I press the brakes, it will drop to 500 RPM, and will idle rough. If I just sit there, it will idle at 900-1000 RPM for days if I let it! Is this a dredded grounding problem?!?!?

 

mine does this a little too. I think its fairly common.
1)Vacuum leak in break booster
2)alternator bad
3)BAC or TPS??? I dunno

 

mine does it a bit too, but rpms only drop a tad before coming back up, if I sit there and pump the pedal the rpm just keeps going up and down a bit.

 

my lights also dim, RPMS stays steady though. I will place an extra ground on the battery some time.

 

I have the same problem in my 89 --
It idles at 1000 but if i touch the brakes or open the roof/windows it drops to 500 then bounces between 500-800, i love electrical nightmares...Personally I thought it was my alternator, now taking other suggestions...

 

I had this problem too. I added some extra "main hot" wires from the alternator to the battery, and it helped a bit... but having an electric fan on a stock 88 charging system, is, well, a bad idea. I put an FD alternator on mine. No more problems.

www.geocities.com/rx7_ragtop and go to the "my car and mods" section. There's a link to a writeup on how I did it. EASY mod, and I've never had any reason to regret it even for a second. I now read about 14 volts at idle, and never go below 12 with EVERY accessory on, lights on, and foot on the brakes when idling.

That's with a big ole' Perma Cool finger-chopper fan. (That's a bad idea... there are MUCH better fans out there...)

Brad