running rough only in low idle

86 PA runs fine in high idle. When drops back down to low idle car shakes mainly when mph are around 45/55 . It seems to happen also when not under load. Car only has 35k have changed about every part in it. Thanks for your time.

to get started, I'd check the engine and transaxle mounts. Also a quick check of the balancer, especially if it's been removed.

[QUOTE=wrightz28]to get started, I'd check the engine and transaxle mounts. Also a quick check of the balancer, especially if it's been removed.[/QUOT

Thank's for the quick reply. I did have the blancer replaced about 6 months ago. The one that was on the car was differnt from the one that was stock. I was told GM updated the part. It seemed to be running like that befor it was changed. I will check into the engine snd trans mounts Sat. Thanks

rough idle can also be caused by old vacuum line/connectors. Have you replaced or checked vacuum lines? Or even to see if one is off a connection.

rough idle can also be caused by old vacuum line/connectors. Have you replaced or checked vacuum lines? Or even to see if one is off a connection.

Had taken car to a couple of shops. They told me they checked air lines, electrical system, and couldn't pull any codes. There for they couldn't find any problems, but knew car wasn't right. I'm thinking of taking it to the dealer. I just hope there is someone who know's the older 3.8.