I have a 1993 Chevy Blazer 4.3L V6 S-10 Tahoe. Currently it is "shuttering" when it is idling. This doesn't happen until the engine starts to warm. After that every 30-60 seconds it shutters with it eventually going dead. It will restart with no problem. Also within the last two days a clank has developed when the shuttering happens. It appears to come from under the floor board area. Blazer drives ok. Shifts ok. What is this????

 

Sounds more like a problem with the engine than the transmission. Is the problem present while idling in park or with the transmission in gear?