*are you putting the ECM into diagnostic/tune mode (it won't accept a new tune without it - there's a post showing the procedure and it's dead easy) I have a theory... how much advance/retard adjustment do you have when the distributor is in the 'right' place? Is it full advanced or retarded? Try the following - remove the distributor and point the rotor away to 180 degrees from the 'right' location. It will not point exactly 180 degrees as the distributor drive gear has an odd number of teeth so it's more like 170ish degrees (I'll get down to calculating it one day but it really doesn't matter) If you have installed it correctly you should have wriggle room for advance and retarded timing adjustment. Put the ECM into diagnostic/tune mode and see what gives. You don't 'have to' swap the plug leads to correspond to the altered distributor position, but it'll save confusion later when you work on it.

*with the distributor installed out of sync when TDC is set correctly, it pulls the timing out half a tooth. This forces the advance/retard adjustment to it's furthest limit without scope of adjustment. I've run into it once before and it took 4 hours of me wrestling with something as simple as dialing in base timing. When I finally spotted it, I got the engine to fire perfectly first shot

**If you have nailed it - stage 2. How to perform a dynamic tune (you'll need a dwell/tachometer to check engine rpm) Engine running, ECM in diagnostic/tune mode: hold the throttle open @ 2000 rpm and gently swing the distributor adjustment between advance and retard until you notice an engine rpm jump. Back the advance off a touch and lock the distributor in place - test drive. If you have found the sweet spot, the engine will pull through it's rpm range faster and changing gears will feel stronger. I would also regap the plugs (undersize the gap approx 0.05mm) and use premium grade fuel (88-90 octane seems to be most beneficial) Happy motoring