Sorry to bring back an old thread but I just wanted to post that the plug for the TBI throttle position sensor is the same as the three wire coolant sensor. I'm sure the info should be useful to someone sine the connector cost 55.00 from a stealership. If you don't have your old TBI harness around you can order TPS plug from summit, 6 bucks I think.
1991 Silverado-L33 5.3L, 212/218 .557 .562 115+4, ASP under drive pulley,180* thermostat, 90mm truck intake w/ LS3 throttle body. Shoenfeld conversion headers and duel Flowmaster exhaust. Performabuilt LVL 1 transmission and 23-2500 stall converter.