Good advice deserves credit. My Delorean was giving me fits. I could not find out why it would stumble and misfire during acceleration. You could take the throttle in hand and it would not even try to get up to speed. I looked for vacuum leaks and found the vacuum advance was leaking. Checking with John Hervey he said it likely wasn't that since the vacuum advance actually was for coming down in speed not to replace the mechanical advance in the distributor. He recommended I have him clean the Frequency Valve in case it was plugged up and not allowing fuel back to the tank. So for $35 I figured it was worth the try. Got it back in 5 days, put it in and the car ran the best it has in my 7 years of ownership. Probably had been plugged up since I brought the car back to life after sitting for 10 years. Garry