I searched for some info and really did not find anything that works for my problem. Some info: 1991.5 4 speed auto (do not know model #), just changed fluid to Mopar +4 and filter. I start the truck, apply park brake and let idle 1 min to fill converter. When I first start off if I am on a slight hill the truck will not move with out a lot of fuel. Is it the clutches slipping or not enough pressure? Once the truck has 30 sec. of operation the transmission works fine. Thanks for all the help.

 

Mine will do that when cold. I always let it idle for about 5 min. or so in N before trying to drive when it is cold.

 

Its the check valve going to the converter. It's not holding fluid and it allows the converter to partially drain down when the truck is not running. The pump doesn't pump oil in park so it take a few seconds to fill the converter back up before it will go. When you put it in neutral, the pump fills the converter then when you shift into gear it is ready to go.

Mine did this before I had it (the tranny) rebuilt the last time. Works fine now.

 

Classic converter drainback, there is an Upgrade Manual Valve available to address this. Sonnex has one but yours has to match the one they sell, Superior also has one as well as TransGo, and Mopar should have one too. There may be others. For a long time drilling a certain area of the valve body was practiced and this contributed to drain back. Like Paccool said, you should only start the truck in Nuetral. Then the transmission is actually pumping oil to the Torque Converter circuit. It should take only a minute or two at the most. 47 seconds +/- is the actual magic number I think
If the transmission is continually started with the Torque converter drained back so-to-speak, the converter will heat up, prematurely ruining seals etc and eventually failure of something will result.

Here's an excellent read on the Dodge TorqueFlite transmission on the 727, the origin of the later Dodge Transmissions (518,618,47rh etc), it is the best breakdown how-it-works I have seen and the newer 4spds are nearly the same with the addition of the OD tailshaft unit. Good read for any one interested.

http://www.allpar.com/mopar/transmis...-tom-hand.html