ECM Fault - could be TPS

[KasaRyan at aol.com]

My 93 chevy truck with the same TBI engine would do the same thing sometimes 
after washing the engine.  It turned out to be the water messing up the 
Throttle Position Sensor.  If you have really hosed one good you have about a 
30% failure rate on it!  The computer sees the changing TPS value as you 
moving the throttle and incorrectly alters the a/f ratio to compensate.  Then 
it sees that that messes up the idle speed and o2 reading and alters the 
injector pulse and IAC position to account for things.  The result is that 
the engine may run crappy at anything less than 75% throttle for no apparent 
good reason when the problem is just the TPS.  Use a scantool or a good 
voltmeter and make sure the voltage is linear with motion and unchanging at a 
fixed throttle setting

Ryan Hampl