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We have a 1990 Bronco with a 351. Since we got it, it's had warm start issues. It starts great when it's cold, and starts great when it's hot. But if we let it sit for a couple hours, it takes much longer than normal to start. It might take 5 seconds of cranking to get it to catch. Once it's running, it runs fine.
This is what's been done lately:
Full tune-up - all filters, O2 sensor, plugs, wires, cap, rotor.
Took off the throttle body and cleaned it out real good with a stiff brush. Also soaked the IAC pretty good and replaced the TPS. It now runs and idles much better than it did before, except for the warm start problem.
I've also pulled the codes - nothing.