please help! major electrical problem with my van

Hope someone can offer some insight. I have a 93 lumina van that is having some major electrical issues. The van starts and charges when the engine is cool, but, when it warms up and indicates hot (red lining) on the gage it stops charging this takes about 10 min to occur at which point it starts to backfire you have to wait about 20 mins for it to cool down enought to start charging and repeat the whole thing again if you don't it just won't start without a boost. Test shows that it is not overheating that when diagnostic is done it returned with a MAS sensor problem that was changed, along with the alternator, various cables and wires. It is driving my husband absolutely nuts! By the way, it all started with the fact that my fan wasn't coming on, that works now but it still indicates hot when the fan is kicks in. This has been happening since winter which is below 20 degrees here in canada so I dunno, any ideas????
Thanks guys

This thread has been copied to the Lumina VAN (APV) forum. (when everyone agreed on saying Lumina Van, who at GM had come with the "APV" name ?) Please check replies in the Lumina APV forum
http://www.automotiveforums.com/vbulletin/showthread.php?t=699204