My friend has a 2000 alero (4 cylinder) and it gets damn close to overheating. the temp will sit at normal spot when driving but it will climb almost to red sometimes, especially when sitting in traffic. waterpump is new, so is thermostat... problem still exists after fixing both of these. the dealer says its the gauge... ive never heard of a gauge going bad like that plus it seems like its working fine, its not like the needle doesnt move. any ideas im stumped

Sounds like it could possibly be the cooling fan or the fan relay. My 99 does the same thing, but I have the 3.4. Eventually, the fan comes on and begins to cool things off.

I just had this problem just this week. and my car was red-lining...
I fixed the problem with a new rad cap. The seal was shot. Give that a try.