Bruce this doesn't sound like an electrical sounds like valve timing and it could be from the timing advance @ the distrbutor (although I'm not sure how the lean burn system handles timing advance it may be eletrical as in today's cars)) or timing chain streach. Put an induction type timeing light on the car and fire it up and watch the timing mark. does it jump all over or stay in one place as long as the engine speed remains constant? ( if its sporatic I'd check the chain) Rev the engine and watch the timing mark it should smoothly clime toward advance as the ending speeds up and drop back down as engine speed decreases. If it doesn't move or jumps I start looking at the advance mecanism for wear, sticking, or electrical signal from the lean burn system. I hope this helps. Joe '76 nyb bruce Stubblefield <audiblefeast@xxxxxxxxx> wrote: > Hello list, > After having my carb rebuilt by a carb shop that > has always done well before, the mechanic there > insists that there are no vacuum leaks he can find > and > that he suspects the rough running to be an > electrical > problem. The plugs, sparkplug wires, distributor, > etc. were recently checked and wires and plugs > replaced(by a different mechanic). > Is there a way to check the lean burn computer to > see if it is working properly? The car randomly and > sporadically loses power and/or knocks terribly at > 50 > to 70 mph, then after a few seconds or after I back > off the gas and step back on it, power returns to > normal and knocking stops. I'm not talking about > knocking on hard acceleration, which it normally > doensn't do. Also, at low speed coasting, hitting > the > gas occasionally causes a popping out the intake of > the carb. Sometimes is blows off the air intake > hose > attached to the horn of the air cleaner assembly. > Seems like I need to go over the electrical > system another time. Greatfully accepting comments. > > Thanks > Bruce S > > __________________________________ > Do you Yahoo!? > Free Pop-Up Blocker - Get it now > http://companion.yahoo.com/ > >