cm1

Hi guys new here, I'm impressed with what I, seen so far.
Here's my problem 2000 GMC sonoma 4.3L 4WD, we replaced the rusted out fuel tank, &1 of the hose connections broke, so also did sending unit.About 2 days later came back with ck eng light, codep0452 evap pressure senser low, did diag. tree came up with bad senser, disregarded becuse new (silly me).Tightened & cked all connection, cleared codes, let go.
Came back same code, did smoke test, purg selenoid leaking, replace seleniod,& cleared codes agin (solas pro scaner).
Came back same code replaced sending unit. cleared code. Did drive cycle,by the book 30mi.,no light. Returned.
After he filled it that night and drove for awhile he parked it for the night, & refilled in the morning the light&p0452 came back (approx180mi).

I,m about ready to pull out my hair . any help would really be appricitated.

New info : light only seems to come when the A/C is on ?????????????