[grinch4om]

when you unplug the ECT, it tells the computer the engine is real cold, thus throws more fuel at the engine,(pulsing the injectors more rapidly and or holding them open longer) if it runs normal when you do this, look for a vacuum leak...bottom of intake? Fords say cold when unplugged (ECT), find out what GM does, if it is opposite, it would lean out a fat mixture, either way, I would check the ECT first with an ohm meter if it is ok, go after the above.