Code P0455

P0455 code evaporative emissions system leak detected large leak, I've had the cylinders cleaned they were completely clogged with it look like sand and inside of there was all and water just everywhere. I put a new gas cap on I'll change all of the spark plugs and wires, I've changed all the coil packs. I've changed several sensors. When I go up a hill my car like boggles out real bad it jerks it loses power when I first crank it, it boggles out. I'm scared that I'm going to tear my car up, I don't know what else to do. The mechanics in the small town I'm in there are only two and they are so backed and booked up that there's nowhere for me to take it to. So, I have you know what they call shade-tree mechanics that worked on it please help me if you can.