3S-GE high rpm choking.

[Kiddy]

Hey there guys. I have a 3S-GE off a ST202 and it's running sweet until I changed the bleeming fuel pump. Everything started choking at 5000+rpm and I couldn't get the engine to get to higher rpm. I had the fuel regulator replaced with an after market one and still the same thing. I thought, bummer, I must use the original pump then. Nah, Nothing happen, still the same. One major thing. the engine revs fine at 1st gear or when at no gear at all. Which means only when on load this problem occurs.

I have done the following diagnostics. Fuel pump voltage is constant no matter at what rpm. Fuel pressure drops off at higher rpm(checked this out at the fpr).

Help.