I have a 91 accord 4 cyl. I have converted into a parade car for the shriners. it has 40k on a rebuilt engine and auto trans rebuild too.
when I start driving it runs great at all speeds...then when I get to the parade, and drive in a parade for a half hour (at idle speed) it then starts to shudder real bad and the tach shakes violently. then when I leave the parade it continues to do the same thing as I speed up (tach hakes violently like it cuts out of gas ever 1/4 or 1/2 second.) but then if I stop and turn it off and let it cool down for 10 or 15 minutes it either runs great again, or runs great for a few miles then starts to cut out again. I have replaced the plug wires and plugs, had a full tune up, new air filter and even a new fuel filter and nothing has fixed it. I even run premium gas in it... could it be a vacuum problem? I have a great honda mechanic and he is stumped too...any ideas?