My cruise control completely freaks out over 80mph. Any thoughts?

Also, 75% of the time, when my second turbo comes in boost leaks out somewhere and I drop to about 5psi. The other 25% of the time the car takes off like a bat outta hell. I've got plenty of mods, and the car just got an expert tune up, but the turbo problem didn't go away. Any thoughts?

 

The cruise control problem may be related to the boost problem. I would figure out the boost problem first, and then worry about the cruise control. The boost problem could be caused by a number if things. Most common is the y-pipe coupler. After that, it could be any number of hoses, solenoids, pills or actuators. Here's a good place to start...

http://www.autosportracetech.com/RX-7/rx7stuff.htm