Does the check engine light stay on after you try to start it?

Maybe while you're waiting for the tech gurus on here to figure this one out (they really do know all there is to know about monteros!) you should try disconnecting the battery for an hour, turning the key with the battery disconnected, and then reconnecting the battery, just in case the ECU needs to be reset. My guess is that it won't fix it, but it's free and easy and eliminates one more possibility from the list of possible causes!

Jim

1994 Montero LS