[J-Ri]

If the problem started immediately after installing the new alternator, then 99.9% of the time it is either something was damaged during the install (or it was already bad and a simple nudge pushed it over the edge), or the new part is bad. I'm assuming that since you listed it as a possibility, you checked for anything around the alternator that could have been broken or disconnected? It's been so long since I worked on a 2.2 OHV that I can't really think of what's over there, just check everything if you didn't already. The other possibility is that the alternator is leaking enough AC voltage that the PCM isn't getting a good DC signal back from anything as it should. The other .1% is that something just happened to fail at the exact time that the alternator was replaced. It happens. Diagnose it just like you would a Honda, they all work the same... suck, squeeze, bang, blow! When the battery was replaced, the body ground that connects to the battery tray may have been damaged. The tray corrodes from battery acid vapors condensing over it, and the ground can come loose. I knocked one off while replacing the fan once, had similar symptoms to yours, only adding that it was very hard to start. I cut the cable at the ground, installed a new end, and ran a new cable from bat- to the new ground on the upper radiator support where the two cables were joined. There probably won't be much left of the tray there if the batteries had been neglected for 10 years.