Here are the codes I'm getting:
p0455 - large evap leak
p1451 main control (evap canister)
p0306 - cylinder 6 missfire
p0174 -- bank 2 lean

are these all related? Or two separate issues. I have replaced all the evap lines with new lines. I have a new egr valve, and exhust manifolds, and what should I look at 1st

 

What the code 455 says a large leak when the system is tested by the computer.
1451 is the canister control 'circuit'. 455 and 1451 might be related.
306 cylinder 6 misfire. Fix this first.
174 might be due to the 306 misfire, otherwise a vacuum leak or a lean condition has shifted the long term fuel trim table for bank 2.
Treat all codes as separate.
Good luck.

 

I cleared the codes and so far the only code to come back is the evap solenoid, since the wire lookd good, and the solenoid is very rusted (only that and the fuel pump is original from the cab back). I ordered a new one from amazon, should be here on thus day. Should be a simple fix with all luck. Then I'll see what codes pop again

 

The P0455 is sometimes set if the gas cap isn't on tight.

 

Update: I replaced the selonid and so far no CEL, though I still seem to have a slight miss in the engine when damp, until it warms up. The old selonid was definitely bafmd, it actually rusted through.