4.3L V6 4x4 ZR5

Okay so it used to be i'd wash my truck and i'd misfire right after, then it turned to every time it rained. Now it's constant so it has to be electronic but i can't figure out what it is. I've replaced plugs, wires, distributor, and rotor i'm on a tight budget so i need to figure out exactly what is wrong before i replace anything else. I'm still throwing a P0200, and P0303 code on the OBD. If anyone has any ideas of what it is or could be PLEASE let me know i have to drive this truck over 200 miles one way to pick my daughter up friday.