I have 2000 Frontier ( 4 cyl.) that has 104,000 with very little trouble. But, when there is rain and the engine is cold, it runs very rough until the engine is thoroughly hot (about 20 min). Has anybody had this problem, and how did you fix it? Thanks very much.

My truck was doing the samething. I found it to be the fuse block right their on the dash, left of the steering wheel. When you first start it and it runs ruff try pushing the fuse block, if it clears up you will need to change outthe block. I cant tell you why but it only didit when it rans. Weird problem to have.

Thanks lateral! That is weird, but I've eliminated the distributor, so I am looking forward to rain to give it a try!