Here's an interesting condition I am experiencing with my 94 Accord (4 cyl VTEC, 180,000 mi): The car runs smoothly during cruising conditions and still has good power but, when I am at highway speed and let off of the gas, the engine runs slightly rough. I checked one of the plugs and it's good, the distributor cap and rotors were replaced a couple of years ago so they should be ok too. However nothing has been done to the fuel system since I bought the car at 100k. Any ideas out there?

 

Late late followup for anyone wondering what went wrong.

Cause of the rough running was the EGR ports were heavily coked up. Fortunately Honda has an access port which is removed and cleaning can be done. Car ran great after EGR ports cleaned. Valve still good!

 

Thanks for posting the fix. EGR port clogging afflicts many Honda/Acura products.

regards