high idle sputtering on LS170

[grunex125]

LS 170 skid seems to loose power and sputter at top end engine rpm, acts like it isn't getting fuel, and wants to stall out. I've changed the air filter, fuel filter, the engine has a newer aux fuel pump which is supplying fuel fine to the best of my knowledge, and fuel pick up tube is attached fine in the tank. I can run the engine for longer durations on 2/3 throttle with very little problem just can't run full throttle when I need to or this seems to happen. Some of the things I feel may have been causing it may be oil pressure sensor trying to shut down the engine, or possibly a turbo getting worn out......I have no way to measure turbo boost but it seems to have a decent whine to it and no play on the impeller. Any thoughts on what else I can check or do to run a check for figuring this one out? I should also mention I have new fuel lines that aren't leaking or seeming to pull air into system. but the effect I get is similar to a system with air in it. exhaust smoke is normal and not abnormal, any thoughts?