Look at you air mass meter. If the adjusting seal has never been broken it could stil be sick. I purchased one (used) for $100 the seal was broke & it didn't work. Anyway it sounds similar to a problem I had. In the meter is a very thin wire (I forgot the type of metal)and this must heat up just right for the air & fuel system to work. While you're at it replace the main fuel pump if it has many miles on it. My 85 with 240,000 had rust in the pump. Too, the intank pump (less expensive) should be replaced. The rubber sleeve that connects the pump to the line is probably rotten. Happy sailing. Hugh Sr.