Tronick

Okay, My '89 GT has a problem, it's been doing it for a while and now I think it's getting worse. My check engine light comes on and goes out under "lugged acceleration". It's a 5 speed and basically, if you're cruising at a consistent speed it's out, but if you give it a little gas it comes on. Goes back out shortly after letting off and returning to a cruise. It won't come on at high RPM as I shift gears, usually only under mild acceleration. At the same time, when the engine is lugged a little, it shudders like a misfire. When I say "lugged" I mean cruising at about 45-55 in 5th and just applying a little gas to accel. Will do the same shudder in 3rd gear around probably, 35-45 or so, usually when the engine is between 1500-2500 RPM, and the car will shudder, and the "check engine" light comes on. Let off the the gas the light goes out. The computer isn't storing any codes so far. What do you guys think???? BTW, I'm reading my post and it would seem that I just don't know when to shift a 5 speed, I can assure you thats not it. This pony is the 6th one I've owned. Here are some details about the car:

302 + .030
B303 cam
10:1 pistons
1.7 rockers
BBK equal shorties
Flowmaster dual 2 chambers
Had a MSD coil, but it started arcing inside the coil, you could see it at night with the lights out, so back to stock (BTW, it had the same symptoms as above with the MSD)
Stock intake, and E7TE heads for now, I know that B cam is probably costing me more horses without a better head/intake setup, but it will have to wait.
91 octane all the time, timing changes have had little to no effect on symptoms

blowninjected

It could be a clogged injector...I have an '89 too and my check engine light has been on since I bought the car. I checked this and checked that and pretty much checked everything and its still on...I just ignore it now, no sense in getting all bent out of shape over it. Good luck