Was your oil light coming on while you were driving or just trying to crank the engine?? Its normal that your light would come on if you are having problems cranking the engine over. Usually the ECU won't even let the car start if there's and oil pressure problem, but since you already got out to the highway, that's probably not the problem........Could be a speed control sensor problem, or maybe a multiple cylinder misfire. I had somewhat of the same problem after I got my car back from my build-up. Would drive fine at first, but as soon as I got to steady highway cruising and the ECU started running it's test programs, everything would go haywire. I went out and bought one of the top-of-the-line OBD II diagnostic tools with real-time display and easily diagnosed the problem and fixed it. I'd recommend getting a scan tool for the future, or to anyone with turbo for that matter. Even if its the cheaper $150 ones. Inevitably, you're going to run in to problems here and there, and it helps BIG TIME in figuring out what's going on and fixing it yourself instead of having to go into the shop all the time.
