Recently bought some rebuilt and refurbished 4 ports from Bosch about a week ago. Ever since the install the 98 Cherokee has ran like ***. Blue smoke, sputtering, backfiring, terrible throttle response, heavy vibrations from the engine itself, to the point I haven’t ran it in a week to make sure I don’t blow it up. I got an error code for injector 4 but after running it for awhile it went away? But it still idles and coughs and runs like hell. I think the smoke and smell is it running rich but again, I’m not risking a head gasket. Any thoughts and ideas?

This happens way more often than you think it does. Reinstall your old ones.

You could have some injectors stuck open and just spraying fuel all the time .