Jane Snyder

My boyfriend doesnt speak the best english so i have the task of fi dout i fo on this issue.
he's got a 99 6.5 turbo diesel that the motor got a cracked block so we found a 1994. 2500 diesel for the motor which was still in and sounded great had all the.maintenance history since new anyway as soon as they motor was installed it would buck when you released your foot from the accelerator pedal, not upon accelerating just when you leave up on it a bit so we took it to a diesel only garage that said the pdm harness was melted which was reloated by the po inside drivers fender. We got a new cheapo 1 on amazon which he said didnt even start the truck when he plugged it in. Yikes i knew we should have not gone with the cheapy. But oing to buy another one but another question is there anything that might not be compatible from the early gmc model motor that was out in? Bad time to ask I guess. From looking on the internet trying to troubleshoot it might be a good idea to disconnect the crank position sensor and optical sensor individually to be able to rule them out also maybe a tps could be the culprit but the fact that the harness to thw pdm was melted generally means the pdm is bad. Any ideas or suggestions would be really appreciated.