First off, I drive a 1988 GTA with 5.7L
Just got finished installing some SLP headers (took about 9 hours) and when I took it out for the test drive, it was idling really rough like it had a huge cam in it and also it felt like it didn't have power brakes. Had to put the ****er to the floor to get it to stop. Checked for pinched lines and would cause. Thought it might be a vacuum leak but not for sure. Any suggestions would be great.

 

Did you reconnect your 02 sensor (dumb question)???

Did you cross any wires from the install??

 

That defiantley sounds like a vacuum problem to me. If you breaks didn't work that good and it was running really rough? Sounds like you might have knocked a vacuum line off somewhere.

 

the only thing i can think of is the main vaccum hose on the top of the booster.

did u install slp 1 3/4? if so u did you have any problems.

 

Found the problem. I had left off the brake booster vacuum line to the plenum. Yeah they were 1 3/4 SLP's. No real problems installing them. Only problem was the far rear bolt on the pass. side of the header. Was just hard to get a wrench or socket on it.
Took us about 9 hours all together.