93 xlt bogging problem

i have a 93 exlorer xlt. when i first start it it will have all power, but after driving it for a while, it will start to bog down when i try to accelerate. when i push the gas hard it will not go and just sputter, but if i turn it off and coast in nuetral for a little, then restart it it will run fine for awhile. the slower the speed i go the sooner this will happen. the check engine light will come on when this happens.i was told it could be a clogged exhaust. it has 185k mi on it. is this what the problem could be? is it just the cat?

Also when it is in 4wd and i turn, it will make a grinding noise by the wheels, what is causing this? any help appreciated!