could be anythin
its running rich yu say? Yu might want to remove the throttle injector unit and check the pre heat screen under it. Some have pre heat screens under the TBI unit and some dont, see if any of the gaskets are cracked around it, also, one of the injectors can be bad , instead of pulsing it could be just open and dumping fuel, ill get back when i have more ideas. Its midnight now , have to go home.