You need the ACT and ECT sensors for the car to run. When my ACT went bad, I knew it because the car would not run at all. Once you get all the timing issues squared away, just do the standard resetting of the computer. The EEC-IV is always kicked in. That's what runs the engine. Leave the chip out until you get all the bugs worked out of the stock setup.
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351W 89 Mustang GT Convertible