There are two common causes to the problem you are describing. There maybe a problem in the fuel enrichment circuit which is easy to detect in that the frequency valve will buzz full time after engine warm up. The second problem may be an out of tolerance CO mix adjustment. DMC Joe www.dmc.tv ....... Starts Monday June 18 "We're here to help you" DMC Help / De Lorean Services / <dmchelp@xxxx> ----- Original Message ----- From: Jan@xxxx Hello everyone, I need some advice for my car: I had the Cat replaced by a pipe a couple of months ago (which is legal here) to get a little more performance out of my car. This DID do the trick, not much, but noticable enough. The car was behaving beautifully when I got it back from the shop untill about three weeks ago. When Idling you can smell some unburned gasoline from the exhausts (and no: I'm not kneeling down to notice) and I get VERY frequent backfires. I even get them when taking my foot off of the accelerator at as little as 1500rpm. This backfiring is nice when you want to impress your 7 year old cousin, but that's about the only "pro" I can think of: it is not supposed to be this way...