I have a 1995 Dodge Ram 2500 series pickup. 4x4. Auto trans. 5.2 liter V-8
86k miles.
Shifting problem: Code #34
Symptoms:
Usually shifts from 1st to 2nd o.k. rpm can reach 3500 before it will shift into 3rd. 4th and o.d. shift normally.(this is an intermittent problem). Sometime will not shift out of first gear until rpm's are very high. If I use the accelerator gently, it will shift correctly most of the time. If I press down hard on the accelerator, such as shifting into passing gear, it seems to start the shifting problems I just explained. Next time I start the truck it will shift through all gears perfectly. Code #34 still lit. I don't think it's the transmission that's the problem. I get no slippage and when operating normally, it shifts perfectly. Could it be a sensor?
Thanks;
Jake...

I changed the transmission filter and fluid. I also replaced the speed control on the transmission