rough idle, rain, bumpy roads

Ive got a 2000 Silverado 4X4 with the 327vortec in it (auto trans).. Ever since I bought the truck, its had a really weird problem.. Anytime its real wet outside, or if I go over a really bumpy road.. It will start to stumble and miss a lot..

Ive checked all the ignition wiring and connectors, and checked out all the wiring etc under the truck.. Cant find out whats causing this to happen..
Its really starting to be a problem now with all the snow melting, and all the roads being so wet..

the engine light has always been on, I got it scanned once and it come up as a random misfire..

Thinking maybe Somebody has experienced this? or somthing similar?
Any ideas of where to start troubleshooting??

Both my trucks are disabled right now and i'de really like to get one of them running good

bound to be a loose connection. Have you checked the fuel pump connections at the gas tank?

check the main ground cable and connections

ive checked all the connections I could see just by laying underneath the truck..

I would wiggle them around while the truck was running to see if I could get the truck to stumble..
But so far, nothing..
I did notice that there was a trailer tow package that has some pretty shifty wiring..

Where does the main ground cable connect too?
Im gonna go through and pull all the connections and clean them, and use some ignition protect on them.. hope it helps

thanks for the suggestions!

trace the negative battery cable from the battery to where it mounts to the engine block and check that point of connection

Yeah that's where I was going... all Ground wires. Make sure you don't have any loose fuses as well. Check your firewall too make sure that none of your Rubber grommets are worn causing occasionaly grounding...
For the record i too hate electrical problems.