OK. I took the '91 Classic and had the intake manifold gaskets replaced. Now the tach reads 5-600 rpm low and the engine "pauses" every once in a while. Only when its under way. Just for a second, then it powers back up. Its like the coil is disconnected and then reconnected. The tach goes dead for that moment also. It can happen 10 times in a row and then not for two days. I took it back and they looked at the wiring, the coil, did diagnostic tests. It only will do it when moving, so they were never able to duplicate the "pause" in the shop. It will do it at any speed, in any gear. Its really aggravating. Does anyone have any ideas?
Thanks,

 

I have a 1991 Classic, and from experience can tell you that the symptoms you describe are often due to a failing alternator. The engine will cut-out, the tach needle will drop to zero, and then the engine will start missing. These vehicles depend on a healthy output from the alternator at all times. Go to a auto parts store that offers a service to check your battery and charging circuit (Like Autozone, Pep Boys, etc.) with a clamp on tester.

If the alternator is indeed bad, I have them available as a re-built unit for a good price on my web-site.

The Classic ignition distributor is also known to have failures attributed to the ignition module. This will also cause a engine miss before total failure.

With all of this said, and considering you just had disturbed the wiring around the alternator and distributor when the manifold gasket was changed out ---carefully inspect the connectors to see if one is loose, or if there was damage done to any connectors.

regards,
Geoman
www.eurotekapg.com