88 Ranger wiring issue in rain

[Dunn51]

Got my ranger about three months ago and it runs fine when its dry outside. When it rains the truck will start misfiring and sometimes won't run at all. I started by changing plugs and wires coil ignition module cap and rotor Coolant temp sensor everything I could think of. The reason I think it's a wiring issue is because when it rains the tac will start glitching it won't go up and down smooth. I checked the computer and it's not getting wet I'm out of ideas. It's a 1988 Ford Ranger Stx 4x4. Any help would be much appreciated.

 

[WildSide]

Start by making sure all ground connections are clean and tight.Next make sure all electric connections are free of corrosion and clean.

 

[Dunn51]

I have checked over the harness and everything looks ok and to be tight but the previous owner hacked the harness all to hell. Would like to put a whole new harness in but can't find one anywhere.

 

[monkguru]

I had this same issue, and perhaps I'm going through it again. All I know is it was bad contacts near the coil. On rainy days, I had to sit. I had someone pull all connectors and clean them. He said there was corrosion on wires going to the coil. Perhaps a ground. I dont know. My truck stalled the other day sounded like pre ignition and stalled. I have fuel and spark. Here we go again.