Transmission won't shift 2nd to 3rd

[RICHARD JOHNSTUN]

I have a 4.7 motor Ram 1500. I have just dumped thousands into a new Jasper engine and then "suddenly"had to get new tranny from AAmco. They conned me to getting a different computer first, then the engine. I don't know what all they carried over in parts from old engine to new, because they "don't remember" Now it won't shift from 2nd to 3rd while going uphill at fairly strong throttle. shifts fine at flat ground or smaller elevation. AAmco tells me everything is fine. no codes so nothing wrong.... Until I took him on ride to show this problem. If I recreate for him, it doesn't shift, and will flash engine light when rev gets to about 5500, and engine sounds like it will explode. If I let off throttle enough, it will shift to 3rd and move on. The flashing engine light doesn't stay on. He said some control module on engine tells when to shift, but he doesn't know what it is called, and tells me he will research but never comes up with answer. so tired of paying through the nose for diagnostics and other leaks with engine and tranny, especially when I am unemployed because someone ran me over when I was walking and nearly killed me.
Engine shop says tranny problem and tranny shop says engine and neither will do anything without another fee... Any ideas on what control module I should replace...

 

[FCA Master]

I would not just throw a TCM at this. I would find a shop that can actually do some diagnostic work and give you a definitive answer. The flashing check engine light is from a misfire and may contribute to, or be caused by, the transmission issue. Without some scan data it is difficult to give you some direction. To get started you can go drive it until the light flashes (a code will be stored) then get Autozone, or some other parts store, to pull codes for free and see if you have any codes besides the misfire code or codes. Limp mode on this transmission allows for only second and third gear in forward, so the shift point will be much higher. I hope this helps give you some direction.

 

[fastf]

Those code reader only will give you a code you need one that can read live data and get down inside the computer.