Welcome to the forums Andy.
At that many miles, if the lower intake manifold gaskets were never changed to the aluminum framed ones, then I'd have that taken care of as soon as you figure out the cause of it stalling.
If it runs fine till it warms up, then it is most likely one or two things, the crankshaft position sensor, or the ignition control module.
A guide to testing the ICM, and CKP signals.
One thing to try also, I doubt it is the MAF, but I still cannot rule it out, after doing the ICM & CKP tests, I'd remove the MAF, clean the thermistors on it with MAF cleaner only, if that does not help then disconnect the MAF, and see how it runs in speed density mode, it will not run great, but if the MAF was faulty it should keep running.
When you test the ignition control module, and crankshaft position sensor, let us know your findings, my money is on the crank sensor.
Be sure your batter is still fully charged when performing these tests.