Firing order diagram needed

My 1998 Jeep grand cherokee laredo 4.0l inline 6 will not completely turn over. My fiance has changed the thermostat, changed the spark plugs, did a radiator flush, oil change, bought a new batttery & tested the ignition coil & it still has not completely started but does try to turn over. It overheated and wouldn't restart for about a hour then when my fiance drove it about 4 hours later for about 7.5 miles it broke down again and wouldn't restart. My fiance was able to get a hold of a OBD2 scanner and it did show 3 codes however he was unable to get the codes written down and now it will not show the codes. In the morning we will try the wrench on the crank test and also will be doing a spark plug test from the distributor to spark plugs since we all ready tested the ignition coil to distributor and are getting spark. I will reply with the answers of the above tests mentioned when we have completed. We did get it restarted however it is still overheating and dying. My fiance says he doesn't feel like all cylinders are firing. Could it be a spark plug not fully in correctly to make it overheat and not allowing all cylinders to fire? Thank you for your time. What could it be?

We got the ECM ports reconnected and thanks on the firing order.