I bought an 84 GSL-SE SE about 2 weeks ago. I drove it home about 50 miles and it ran horrible. Idled at around 2000 rpm. I read a bunch of forums and got to work. I replaced every vacuum line under the hood, removed the throttle body and cleaned and oiled it, and adjusted the tps (not sure if I did that right). Now the idle surges from 1100 to 1500 rpm about every second. Another note, a previous owner removed the Mazda ignition modules and replace with GM modules. I plan on replacing with an MSD system, but I want to get the fuel system fixed first. Any ideas?

 

Sounds like you still have a vacuum leak. Did you replace any of the intake gaskets? Alot of people try and reuse them and it doesn't work well

Heck, some people have had to still add rtv to their intake gaskets to get them to seal properly

 

I did replace the intake gaskets, but I had that thought as well. I am going to try spraying some starter fluid around the intake and see if that is what is going on. I can add some RTV to the new gaskets if necessary. Thanks for the input.

 

Well, I spent a LOT more time cleaning the throttle body. Lots of carb cleaner, a toothbrush and a can of WD40. Put it back together and the surging is gone. It still idles a little high, around 950 rpm. I am going to clean out the BAC tomorrow. I will let you know.