[boschmann]

Does this engine still use a knock sensor, it can cause similar problems as it modifies the ignition timing signal? Also, as the base ignition timing & set mechanically and the ECM does all the fine tuning I'm wondering how the timing was checked. If you only used a timing light it may be misleading as the ECM can be adjusting things to look okay at idle when it may not be. I'd go back & set the engine on TDC & check the distributor rotor alignment to the notch on the housing (mechanical timing). What I'm thinking is that the distributor may be off just a tooth and the ECM is correcting enough for idling. But, when you try to drive things go really bad and the ECM can't adjust.