sorry just wanted to repost to see if it is the same as above.....
Hey quick question guys first time poster long time looker... i have a 95 Lumina and all of a sudden when i started the car one day(cold) the temp went all the way up to 260 and stayed hot until i came to a light and the heater is blowing cold air(about 30 seconds) i then took off and the temp dropped to a little less then normal and also started blowing hot air... after driving a little more i noticed that the temp is up and down and so is the heat blowing out of it (hot then cold then back). after about 30 min driving the engine will finally totally heat up and blows out hot air (less extreme fluctuating). I took it to a well trusted and used mechanic who replaced the T-stat last year. i told him what was going on and he bled the system of air. i got it back and he was still confused so he replaced the t-stat (free of charge) and it is still going on.... he started looking into it more and called around to different places and he doesnt do head gaskets but both the people he talked to said it would be the head gasket. he said he pulled a couple plugs and there was no anti-freeze in the oil. SO i'm wondering if this sounds like the intake manifold gasket as described in other threads... i did bring it up to my mechanic about being the intake manifold gasket... he kind of looked into it and i think shrugged it off... ANY HELP PLEASE SO I CAN DO IT THIS WEEKEND IF NEEDED!!! Thanks Matt