So about 3 months ago my '04 5.3 (see sig) was overheating very erratically. heat would spike then drop to normal then slowly go up etc etc. Changed the thermo, changed the cap, didnt find any leaks. So I take it to the shop my dad and his partners own, and they tell me they've found the problem, it was an overfill hose from the radiator to the reservoir tank, and it was clogged creating pressure in the radiator which made the temp spike. well now its doing it again, and although the shop didn't charge me, fuck taking it 20 min down the road to fix it. has anyone else had this problem? and there are two hoses leading to the reservoir tank, which one would it be that is clogged? I'm sure this happening for the second time means i need a radiator flush, which is coming next.