Nice one Karl, no stopping you now mate!
Vassilli, I've got a '96 Cherokee too; 4 litre, STRAIGHT six, auto. I get what the book says 18 mpg (Imperial gallon) around town, and about 25-28mpg on a run. With cruise control set, at a steady 70 MPH, or thereabouts, I get around 30 mpg.
Like yours, mine needs a bit of work on the ignition - had an untraceable fault on the electrics, which involved ripping out one of the imobiliser/alarm systems, which had been draining the battery, and/or causing the engine to cut-out now and then. Rather embarassing! Now it's an intermittent fault on ignition, which I think is just a lead, but it's been too darn cold to stand around outside trying to find out!