Vacuum leak. Diagnose with spray carb cleaner at all possible sources (that can be reached! Ported vacuum switch is under intake manifold). Isolate everything forward of engine at big take off (passenger intake rail). Don't forget to test fuel injector seals, cold start tube (shoot between cylinders 1 & 2), and throttle plate shaft. Vacuum leaks are a low RPM problem. Bill Robertson #5939 >--- In dmcnews@xxxxxxxxxxxxxxx, "mwwilber2003 <mwwilber2003@xxxx>" <mwwilber2003@xxxx> wrote: > [MODERATOR'S NOTE: The archives have a lot of good information on this as it has been discussed fiarly extensively in the past. The best search engine to use for searching the archives is the Google engine linked on the DMCNews.com web site.] > > > I have an 81 DMC and when it get running for about 10 min or so it > starts to idol very poorly. The oil pressure and RPM's go up and down > while sitting at a stop. When I get going again it goes away, but > every time I stop again it comes back. I thought that it might need a > tune-up but maybe something else. Any ideas??? Thanks > mwwilber2003@xxxx Please let me know what you might think this > could be.