Good Afternoon!

So I got the P0455 code (Evap emission system Leak detected, gross leak/no flow) a few weeks ago after I filled my tank. Then my truck would randomly die as I was making turns. It would also kinda cut out when driving 65mph. Once I get down to 3/4 of a tank or less, no problems at all!

Last night I changed out the fuel filter and the Vapor Canister Purge Valve. Everything I read about this code and dying on a full tank, EVERYTHING said to change the purge valve. After doing this, I went to town, filled up my truck, and last night with temps in the 50s everything ran fine. I thought it was fixed.

Today I'm driving to work, its about 86 degrees, vehicle starts cutting out while I'm driving 65mph, ticking me off as I thought I fixed the problem.

So now that I've changed those 2 things, what is next? What could be causing this? Until I find the fix, I'll just make sure I wont fill up all the way, as there is no problems unless its between 3/4 and full.

Thanks for any help I can get!