Hello. I have a 98 Caravan with a 3.0 and a 3spd. when I got it the trans fluid was brown and smelt burnt, so I changed the fluid and filter. When I had the pan off I found brown sludge in the tranny, I cleaned what I could. It drove fine for a week, but then it started acting up. 1st problem I would hold the gas down and wait a min for it to move. 2nd problem if the gas is pressed down more than half way the tranny jumps to neutral. When I hooked up a scanner I got a code for the torque converter.

 

Welcome to DF
We have gone thru on a early post. First the governor maybe starting off in a high gear and 2nd, Remove the kick down rod or cable at the transmission. When the shaft for the throttle kick down sizes or sticks it will cause the shift level to move into neutral.Code 37 for the lock up could the sludge in the valve body or the lock up solenoid.

 

In addition, a scanner really has no value for 3 speed transmission problems. All the internals are hydro-mechanical. The only computer related function is TCC (torque converter clutch). This part will have no affect on shifting, neutral condition etc. The only real driveability failure would be if the TCC was stuck on, your vehicle would stall when put in gear or shutter/stall when stopping (just like if you had a manual transmission and forgot to push in the clutch).

Very common problem, covered numerous times, about the kick down shaft binding in the shifter shaft. Press WOT (wide open throttle) and the shifter pops into neutral.