Alright, here's the story. My car is an 89 GTUs with 147,000 miles on it. It still has 85 psi on all sides of both rotors. It has new spark-plugs, a new air filter, a header/ presilencer combo (no cats), and a new cat-back. The actuators and the VDI work fine. The timing is perfect. It idles fine. The only problem? 0-60 in 12 seconds on a 50 degree day on flat land. I live 1 mile above sea level just so you know.
So, does anyone have any suggestions about why it's so slow? Would the MAF or some other sensor cause something like this? What about some vacuum leak?

 

85 psi compression is a little low and at the factory limit (85.2 psi is the factory min) and to top that off you are up a mile which robs 2 hp or so for every 1000 ft elevation. So say your down around 12 HP just from altitude and then add in the borderline compression and yep... thats why.

 

yeah, but in the manual it says what the compression should be at different altitudes. It says the minimum at 1 mile is about 65 psi, so i'm far from borderline.