2000 SR5 random misfire

Have 00 tundra sr5 v8 with multiple random misfires. New plugs,coils, exhaust, fuel filter, fuel pump in the past year. The only thing really puzzling was started when we had a good rain. Would go away after the rain but seems to be permanent now. 2 different shops couldn't figure it out. Did see a thread about leak from windshield area and a fuse box issue. Any help greatly appreciated.
Thanks Mike

 

Where'd you buy the plugs? And what is the part number of the plugs? How do the plugs look today?

Any evidence of an intake gasket issue? i.e. hissing sounds?

 

I put in iridium plugs but the mechanic removed them. He put in NGK copper plugs because the iridium need too much power?
Couldn't hear any hissing but my buddy said to start it and spray around the intake to see if it surges. The shop checked fuel pressure and compression tested all the cylinders. I changed the computer with a plug and play one and it runs the same. I did have a windshield leak a year ago, maybe that did it.
I don't have a garage, hoping for warmer weather (snow a couple days ago) to get in deeper.

 

What brand are the ignition coils? I've seen parts store coils go bad in a year.

 

Only use these parts OEM. I’ve listed your exact part numbers too.
I don’t have a part number for the coils as I’ve not yet replaced mine.
Spark Plugs - 90919-01192 (x 6)
Spark Plug Wires - 19037-62010 (1 Set)

 

Are there specific cylinders for the misfire or are you just getting a p0300?