where is my heat going?

93 deville, been chasing down a heat problem and found out it was because i was losing coolant, so i thought..i was in fact losing coolant and couldnt for the life of me figure out where it was going and when my belt was soaked i couldnt figure out where it was coming from..so i was tinkering with it to see if it was the water pump yesterrday and when i took off the res. i seen the line to the rad. was kinked and had been for a long while before i had the car, i started the car and let it warm up with the line kinked, the system would build up so much pressure it would just shoot coolant out all around the rad. cap and not puke back into the res. tank...fixed that and coolant levels are fine and fluctuate in the res. when hot and cold like i think it should

heres where im kinda stumped-i warm up the car and the heat works, i go to the gas station and by the time i get there its not blowing hot anymore(only a 2 mile trip)..so i get out of the gas station and check the temp via data center and it was 181 degrees, i let it idle and it warms up to 203 degrees...i drive 2 miles back home and check the temp again right away and it was back down to 185 degrees...anybody have a clue? all three lines at the T are equally hot...:hmm: