TRUCK WILL NOT REV ABOVE 2000 RPM,ECM HAD NO TROUBLE CODES, on 1995 Nissan Pickup (D21)

cHECK FUEL PUMP, CHANGE ECM, STILL WILL NOT REV ABOVE 2000 RPM. ITS LIKE THE ENGINE IS IN A SAFE MODE OR TIMING IS OFF

3 answers
Check for exhaust restriction.
these trucks had TBI problems
Try checking M.A.F. sensor