Hey guys, wondering if I’m on the right track here. While towing up hill and heavy on the pedal, my throttle started to flutter in and out. It only seemed to happen under higher engine load and it was really hot outside. I cycled through a few different power settings on my qudzilla adrenaline and made no difference until I turned the tuner off and it seemed to go away. 
 

I read on another post I could be a timing issue? 
 

But here is a list of possible conflicting factors: 

-just replaced my injectors and turbo. I was wresting with a hard start issue for a while. Fixed it by replacing the fuel sending unit and tightening the banjo bolt on the back of the head. 
-I just shredded my headlamp to dash wire harness and repaired it. Blew 3 fuses. Everything seems to work now. 

-I have the code P1689 and P0237

-Could it be a ECM, TPS or VP44 issue? 
 

Can’t thank y’all enough for any input

P1689 is a communication problem between the ECM and VP44. So you will need to test the wiring between the ECM and the VP44 with an ohm meter to verify the wiring is good. Should be 5 ohms or less. Then another test is a black probe on the battery ground and the red probe and touch each of the VP44 pins with the ECM still unplugged. These should all be infinite ohms. This just proves no wires are shorted to ground. Double check the fuel pump relay in the PDC bad contacts or weak power could cause the P1689. Beyond that then the PSG on the VP44 could be bad which would require VP44 replacement.