Note on Intermittents
WARNING: This page is about a different car, the 1990 Cadillac Fleetwood and 1990 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
If Code E21 is intermittent, manipulate related wiring while observing ECM parameter P.0.1. Check TPS and TPS test point connectors for shorts to voltage. Cycle TPS through its travel and tap on TPS with a pencil or pocket screwdriver to test for intermittent TPS. If fault is induced, parameter will skip to a high throttle angle.