So I just got done doing a reseal on my motor, and now I'm having problems with my idle. If I apply the brakes, the first pump sinks to the floor, then it build pressure. And when I hit the brake my idle goes down and it almost dies. Now At first I though okay, maybe it's my brake booster, but my rpms drop when I turn on my defrost at full blast as well. I've checked every single vacuum line and ground I could find like 10 times, nothing seems out of place. i have a fresh battery and new cables as well, so my next thought is maybe the alternator. If it's not that, anyone have any experience with this and have some input? I have a 90 loyale spfi btw

The rev thing with the brakes applied points to the booster - make sure the one way valve in the line is working properly - it's under the metal clamp somewhere in the line, I can't remember where exactly.

 

The rev drop with the demist on could be a dodgy earth connection between the engine and the body - look into your earth strap on the engine and make sure it's securely fastened to the engine and the battery/body.

Cheers

Bennie

Brake booster.

Make sure the vacuum line to the booster isn't kinked as well

Did you remove the brake booster line from the car side? there is a check valve in the line; make sure it is not installed backward. I take it this problem didn't occur before resealing the engine.