Before you get carried away replacing unneeded parts, have your computer re-programmed. When the early 90's ECM's are disconnected from power for a period of time they are not able to reset themselves like newer computers are. A common problem is the car is unable to idle, and runs rich. GM dealers only charge about $30 bucks to reprogram the ECM. If the pressure regulator is bad, go to AutoZone, it is a lot cheaper than 100 bucks!!!