[healtoer]

Do you have a blockoff plate for the hood scoop?

 

[healtoer]

Add a blockoff and you'll be good

 

[healtoer]

I doubt the caps are causing an issue but yeah it should be just a regular cap on the radiator, and a "radiator cap" on the expansion tank. I bet that Mishi radiator is fine too. Can you fit the stock fans on it? I do think just the blockoff will solve your issues, however i think a cold air intake will help. When you turn AC on the rad fans turn on and that short ram intake ingests all that hot air.