I have a 91 vette with the L98 motor. The problem I'm having is it surges down the road. It does this in o/drive or in regular drive. The dealership told me it was the transmission. I don't think it is. I think it's engine related. I have replaced the throttle postion sensor, the manifold air pressure sensor, the dist. cap, rotor, wires, plugs, the ecm. HELP !!!!!!!! Sometimes it's hard to start, not often. The radio whines from the engine. I replace the plug wires with a set of racing wires and that tuned out 90% of the whine in the radio. I added exta grounds from the battery to the alternator where the support bracket attaches, and from there to the fram rail. I scraped all the paint and grime off the frame till there was bare metal. I have replaced the egr valve (the code flash on the dash for that). HELP !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!