My money is on a vacuum leak. When the car is cold, the cold enrichment masks the leanness caused by an air leak. Prime culprit is the "snorkel" between the AMM and the throttle body. Remove it and look for leaks, especially on the underside where it may rub against unforgiving stuff.

If that checks out fine, take a very close look at the distributor rotor and cap. A friend had intermittent poor running and stalls which turned out to be caused by a fried dist. rotor.

Lastly - fuel starvation may be at the root of the low power problem. Check the fuel pump fuses, and if the fuel filter hasn't been changed in a while, it's a good time to do it.

Please post back with your findings!
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No one ever went broke underestimating the taste of the American public - H.L. Mencken