01 yukon 5.3 parasitic draw

hi guys
i am thinking i have a parasitic draw and need some advice. I have an 01 yukon 5.3l
my problem first started a few months back. my battery was 1 year old and i went out and yukon i tested alternator and its putting out 14.5-15 volts so i know its working. i took my battery back figuring it was faulty and of course they had to put the charger on it to verify before i could return. it took the charge and held it so now i am thinking ok well something is drawing the power out of it. put battery back in and 2 days later dead again. that was awhile ago and havent had time to check it out.. today i said ok i gonna start fresh, i bought a brand new battery and tested with my meter. 12.49 volts ok good. connect amp meter to it, starts at 2.60 drops to .02 in about 20-30 secs time. im like ok it doesnt seem like any power draw going on here.. watch the meter for a good 5 mins or so and does not change. just to check i open the door and take the reading, 4.26, close door and check reading it drops to .21 once the interior lights go out. now what i did notice is on my instrument cluster once i shut car off even tho i did not even start the yukon today and its ice cold, after about ten secs i heard a small click and seen that the temp gauge goes to about the 210 mark. i first noticed this a couple months ago when this first started happening, i have another cluster i have another cluster and swapped them out. temp gauge didnt move anymore but battery was still dying, when i first switched it out i thought yeah that was it but turns out it wasnt. ok so i disconnected the battery totally for about 30 mins. the temp gauge is still at the 210 mark. i hooked the positive side up and ran another amp draw test. starts at 2.60 and falls to .01 over about 20 seconds and holds there at .01 . what do u guys think, do i have a parasitic draw or that the other battery i had was faulty?any suggestions or theories?