1995 Chevy Camaro Camaro engine trouble on high RPMs

Hello, I have a 95' camaro Z28.
its got more than just one problem.
When I step on the gas and the rpms get up to the 4,200 - 5,000 rpm range the car kinda bogs down and starts making what sounds like a back fire sound. But she loses her power till you let off the gas and I dont understand this. But even when im reving her up it does the same thing. It died for like a year but finally got the thing started again so its kinda confusing just what the problem is, if it sounds familour id love to know.

also dont know if it has anything to do with it or what but one day I started it and a strange clicking noise was coming out of the tail pipes

also sometimes when its running it makes a clicking noice that sounds electical next to the fuse box under the air filter area.

also under the car is a bunch of oil all over like the bottem of the engine and the tranny area its just caked on there.