Engine vibrates

My wifes 94 Chevy Van, G20, V6 has had a vibration in the engine for quite some time now. It is noticable when idling in park and drive. Worse in drive while at a light with a foot on the brake. It is not noticable when moving. The only other symptom the van has that may help you guys to help me is this. If it is allowed to idle for several minutes it will start blowing some blue smoke at the exaust. Then when you drive it smokes pretty good and quits shortly thereafter. Thanks in advance..... Robert Hall

the ENGINE rattles? or there's a rattling coming from up front where the engine is?

i had the same problem, exact problem (not the smoke but...) i brought it to a shop and they said it was the tranny mounts, they were GONNE, so i had to put some new ones in, no more rattles for me, if thats not the problem with you, sorry cant help you :(:(:(:(:(