Toyota Repair: 87 toyota supra turbo, air flow meter, toyota supra

Question
my 87 toyota supra will start up fine and run great until i take it on a drive then after driving for about 10 min the check engine light comes on and the car will rev from 2000 rpm max to 1000 rpm with the gas peddle to the floor.
  The code is a maf sensor code but i have replaced it many times. could it be my greddy bov not recerculating the air back into the intake

Answer
Could be a restriction in either the intake or exhaust system, check the air flow meter to make sure the air door moves freely all the way open, the other cause may be that the catalityc converter is disintegrating causing the exhaust system to get clogged up.