Problem with Purple Plexi 800

[Jayallen]

Just built this Just built this pedal it sounds pretty good. One problem I have is after I play my guitar for a little while then stop the pedal will make some weird crackle sound like when you remove your guitar cord before shutting down your amp. All my cords are new. I re-soldered everything and I re-checked all my wiring. And for the major high pitch squeal I put a 150r resistor on lug 3 than I hooked up the wire on the gain control. Would anybody know what the problem would be? Thanks