1989 running way to rich

Common causes for a rich running condition include: (1) Low coolant level. (2) incorrect temperature range, defective, or missing thermostat (the engine MUST reach 195 degrees or it will run rich). (3) defective or out of calibration coolant temperature sensor. (4) Fuel pressure too high, usually due to a defective fuel pressure regulator or incorrect fuel pressure. (5) Internal engine control module problem (rare). (6) Short to ground in the coolant temperature sensor circuit. (7) restricted fuel return line back to the tank. (8) low engine vacuum due to an internal mechaincal defect, such as low compression or leaking valves; or low vacuum due to an exhaust restriction such as a clogged catalytic converter or plugged/bent exhaust. (9) defective MAP sensor. (10) defective oxygen sensor, or high resistance in the oxygen sensor circuit. (11) pcv clogged. (11) poor electrical ground connection anywhere in the engine control system. (12) dirty fuel injector. (13) Throttle body dirty. (14) needs a tune up. (15) dirty air filter. (16) High resistance in engine grounds. (17) Distributor. (18) Incorrect ignition timing. (19) Faulty PCM computer.

see if you can get any codes , I think you jump a connection and count the flashes on the dash for those . Could be intake leak , you would think that would make it lean but thats what the pros told me for 94 gmc 1500.