My guess is your engine timing is retarded causing the gasoline explosive gases not to complete ignite in the combustion chambers and have their exaust gases exit at the right time.So make sure your engine timing is at 5 degrees BTDC with check engine/timing connector shorted or 8 degrees without as stated in the emissions stickers found inside the hood or in the service manual.
Sidney
Repairs tv's,vcr's,home/car audio out of my home
E-mail:sidneybek(at)yahoo.com
Dartmouth,Nova Scotia
Canada
1985 Toyota 4-Runner,22R-E,W56,RN60LV-MSEK,rusted rear step/towing chrome bumper with 242 000 KM