Alright, I'm beyond upset by now, I did a motor swap, finally got the car on the road and now this. It has a 700r4 that was electronic assist. I have a b&m torque converter lock up kit, the motor is a 305 carburated. Now, when I take it down the road it shifts good, runs good, everything is fine. Then after I drive it like 10 miles or so, park it and shut it off, or let it idle in park, then go back on the road, when it shifts into 4th, it'll bog right down to like 500 rpm, if I press on the gas, it won't rev up, if I keep reving the pedal, it revs up sometimes but then it will die. I put it in neutral, it will turn over but not start until it is moving very slow or stopped, then as soon as it goes back to 4th it does the same thing, and then it won't even turn over. The battery is fine, when I turn it over then, it won't click or anything, it just moves the oil press gauge, but then I let the car sit for 10 minutes or so and it'll start back up and shift again. Im losing it with this car!!! Please help, I have absolutely no idea on this

 

I'm wondering if the transmission is overheating and won't shift until it cools but it shouldn't overheat that quickly. If you manually put it in third, does it continue to act normally?

Also, is that the original transmission and has it ever been rebuilt?

 

Sorry to revive and old thread

Lots of questions. How was the transmission de-computerized?

Is the motor rebuilt? Almost sounds like it's seizing up if it won't crank after stalling. I know it sounds crazy, but if it were my car, I would get a breaker bar and put the correct socket on the crank and see if the motor turns after it stalls. I doubt it, but you never know.

Fluids ok?

The other thing that comes to mind is an electrical problem. Maybe a battery cable or fusible link is getting too hot? Do you have headers? Check the routing of the battery cables and wiring near the exhaust.