Trans Problem

I have a '94 B150 cargo van with a 3.9 v6. While it seems to engage immediatly when shifted into forward and reverse, it barely moves when throttle is applied. There were no early warning signs, such as slipping, etc., but I did notice exessive white smoke out the exhaust just before this happened. Looking for any opinions on what the specific problem is likely to be before taking it to a shop. Thanks.
-Mike

Check the cat to make sure it's not plugged up, that can make alot of people think the tranny is blown up. The motor will usually still rev up in neutral, but will have a total lack of power when in gear. You can check it by tapping it (when cold) with a rubber hammer and listening for stuff rattling around inside of it.

White smoke generally means that coolant is leaking into the combustion chambers. It's possible that you may have a blown head gasket.

Modulator? I had one go on a Pinto back in high school an it would barely move and I had to manually shift it into second. I had no third gear. Look for a vaccum line on the trans and unplug it. If it drips trans fluid, bingo.

iam having the same with my 84 dodge b150 so there maybe 3 to 4 things wrong
the cat or coolant leakin or modulator thats alot of things too look for

No vacuum modulator on Mopar transmissions.