I took the Blazer out last night and while checking the guages that I do every two minutes while driving, I noticed the temp guage was at about 220. Then it would drop down suddenly to about 190, then back up to 230, then back down and so on. I noticed when I hit the pedal and accelerated it would go down, if I took my foot off it would climb back up again. I thought at first my water pump belt was loose so I checked them and they weren't. I think it's the thermostat (even though it's brand new) opening and closeing under pressure. I've heard some people talk about a specific thermostat to use. Anyone know which is the best. It's an 82' 6.2L 85 Blazer on an 82 chassis, 6.2L Diesel, ORD flip, 35's with no cutting on a 4" lift.