I know you've been struggling for a long time with that engine so I won't go into all the questions like how much fuel through it and is there enough cowling exit area, prop size etc. I would send it to DPM. My Moki 2.10 has never overheated and I flew it in 90+ degree weather (harriers, hovering). Try DPM first.

BTW, I didn't have much luck with VP30 w/bypass loop and the tank on the CG in vertical uplines. The thing would flame out everytime. You may be leaning out the engine with that setup. I went to a Cline regulator and my engine never flames out, it runs great. I have my tank right on the CG. Turning a Bambula 20x8 at about 7100 RPM's.