Detroit 60 series from hell

Hi everyone. I'd like to see if anyone has some insight on what I have been going through. I have a 95 Freightliner Classic with a Detroit 60 series 12.7L. Last month it blew the head gasket and hydro locked cyl#1 and threw the rod with piston out the side of the block. Since this truck is my baby. I decided to resurrect it and I brought it to a guy who had a 99 Detroit 60 series 12.7L to swap mine for his.. Well, after all said and done. All accessories ie: AC, alt, idler pulley were all transplanted from my old engine. NOW, my computer was damaged when my 95 motor blew and the 99 motors was stolen out of it, we put a DDEC IV. Truck wouldn't move. Not even bobtail. As soon as u came of the clutch and hit 1200rpm, truck would fall on its face, bellow out blue smoke out the stacks and pop and backfire so violent that it blew the 90's elbows off the mufflers.. Here is what I changed since that day. 6 rebuilt injectors clearance set to 80mm and they were calibrated to the computer, the SRS & TRS, boost pressure sensor, new return check valve, fuel filter, air filter. STILL SAME PROBLEM. So now what I did was put a DDEC III in it and it actually runs with or without a load and only breaks up very little till it warms up to 100 degrees. But. Truck has little power. Since its DDEC III it only puts out 430 so at 1700 rpm in 9th it gets lazy. Everything on the computer is unrestricted and wide open. Motor is non wasgated I know I should be able to get 470 out of it. Anyone have any idea why a DDEC IV won't work on my motor only a DDEC III will? I'm so stumped and have lost about 50 days of work. Thanks for reading

 

I brought it to the dealer, they could not extract any codes. I have their same computer capabilities. Their logical response to my problem was "I don't know, you might want to start at the harness". NOTHING IS WRONG WITH MY HARNESS. I appreciate you're response boxcarkidd, but 14L engine is another animal.

 

I will most deff look into it. Thank you

 

Got it thanks, the DDEC III that's running the truck now seems to be doing ok, but definitely not running at full power. And it's weird, from time to time at 1700 rpm under a hard pull, truck will get power and lose power. Closest thing I can compare it to is anyone who has ever drivin a Honda with V-TEC how it kicks on at a certain rpm. Well that's what it's doing.

 

The engine is a fresh rebuilt (if u will) it was completely rebuilt top to bottom. But it sat for 1.5 years till I bought it and installed it into my classic. TPS huh? Would that be the accelerator pedal? Because my truck would sometimes ghost idle up on its own. (With original motor)