Have an update about my problem re: the 89 Cherokee Pioneer 4.0 I got about a month ago.
It's no longer belching black smoke. However, upon acceleration, it smokes. We found a clog in a vaccuum line, and the mpg went from 5 to around 10 mpg when corrected. However, now, a week after fixing the vaccum line clog, we've dropped to 4 mpg. It no longer smells like it's running rich.
So far this is what we've done: Changed oil (& filter), air filter, plugs, plug wires, and oxygen sensor. Put a fuel treatment in.
Am going to park it, I suppose, and use the parts off of it to fix the front end damage on my 91.
Hopefully I'll be back in my 91 Jeep by spring. I'll be driving a

Nissan Sentra until then. Bummer.