Siezed screw in 2.8 plenum

I'm experiencing starting problems with a 2.8 MPI. I have a donor car from which I was going to rob the IAC motor, and upon inspection one of the two screws holding it in had been snapped off at the screw head.
Then I looked at the actual car I'm working on and it's the same exact deal. So far, just the one screw apparently has been adequate to hold in the IAC to do its job. But I'm apprehensive about attempting to remove the one remaining screw for fear of it snapping off as well and having BOTH screws snapped off, a big hassle: Would applying heat to the surrounding aluminum likely allow it to be loosened? I know it's just electrolytic corrosion from the dissimilar metals. Since both of my engines had the same thing, I'd expect to see this in junkyard engines as well. As an aside, anyone know what else might make an '88 2.8 take up to 5 seconds of cranking before starting--then run perfectly normal after that? I usually have to give it a little gas before it will start, no codes. TIA
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Try soaking the screw with Blaster penetrating oil a few days before trying to remove it. Then before loosening the screw tap it a couple of times on the end with a hammer, this jars the threads and helps break the corrosion loose.
The only thing that comes to mind with your starting problem would be the tank mounted electric fuel pump.

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