motor swap questions

i am looking ar a 1997 cherokee with some engine problems. apparently, the water pump went out, causing the engine to overheat and cause more damage. the waterpump, head gasket and freeze plugs were replaced, but now, "The car is currently running sluggish, when you step on the pedal, she does not repsond very well, however it does run and drive." i'm thinking its a cracked/warped head??? any ideas? I have a 1989 parts cherokee with a good runing 4.0. if it is a bad head, can i replace it with the one from the 89??? If its worse than that, can i just swap the whole long block?

anyone?

needs to be 91 or newer i just put a 93 motor in my 98 but i know you need a hi output.

OK first, bumping threads is frowned upon. That said, do a compression check both wet and dry and post the numbers back here.

Just a thought. Antifreeze and O2 sensors don't get along.

I have the crank, rods and internals from a 2001 that had the same problem. When they overheat bad enough they crack the block (cylinders 1 + 6) before they hurt the head. If the comptession or leak test gives bad numbers you are probably looking at a replacement engine - as stated a 91 up is a bolt in. the earlier engines (head and intake manifold) do not match up and in most states won't pass emissions.