noise?

Hello all, I have this crackling backfire kinda of noise only when i rev the engine up high, it only does this when i step on gas real hard, its fine with normal pressing of the gas. I know some of ya out there might say. well dont rev it up so high..lol. but could this be an exhaust leak i have which is a crack on top of exhaust manifold?. cause other than that everyhting has been tuned up and runs fine...... 1995 jeep cherokee sport 4.0 I6 4x4 , Any inputs are greatly appreciated

Might be a clogged cat or just worn spark plugs.

How high, to what RPMs are you revving it?

How many miles?

As Aloha hinted, how long since a tune up?

Hello, i am not sure the rpm's, i did a complete tune up this spring, replaced fuel filter,plugs,cap,rotor,air filter,wires,. also had radiator replaced with all hoses,heater valve,t-stat,waterpump, due to running hot near the red line. but back to the subject i was revving it up under the hood with the throttle when i was changing the radiator and noticed it amkes that crackiling backfire type of noise, it only does it when i rev it up real quick and hard, my jeep sint here right now but when i get it back tomorrow i can see how many rpms it goes up to when it does it , but if any other info needed let me know, i am not that mechanically inclined, ( friend did all the tune up and heating issue)...Thanks all, Sorry it took soo long to respond...169,000 miles