power dips during constant throttle

[kamechikara]

help pleasewhen cruising with the throttle at the same position in any gear, my sr20 will have power dips. The revs do not drop but the power going to the wheels will periodically go up and down for no apparent reason. nothing like the boost level or revs change but power will kick in and out usually slowly and the gas pedal can be a bit un responsive after a dip. is this possibly the tps or maybe an ecu issue? i thought it was the mafs but even after an safc intall new mafs and tuning the problem remains. any ideas how to figure this one out. my 1st shop couldnt do it. thanks!