The other night Lakeville and I installed a 180 t-stat in my car. One of the supporting mods for the hopefully soon to come 3.5. Why does the temp guage still go over 200 at idle with the 180? When i'm just cruising it stays at 180 but if I go WOT it will go to 195 or so. Shouldn't it never go any higher than 180?

If your car does sit there, it can get that high, and under WOT, it will go up.

After it reaches 200, does it go back down after a minute?

At idle it gets up to 210*. I was at a drive though for about five min. and it went up that high. I don't know if it would've gone back down because as soon at I took off it did go back down to 190 ish. :?

Stock fan turn on points are 215. At speed the rushing air cools your coolant to the rating of the thermostat (in your case 180) however when the wind stops rushing (idle or in town driving) your car will heat up until 215 and the fans turn on. A custom pcm with 180 fan points will keep your call at that temp or you can get manual fan switch.