'90 xj wont start!!!

Hi everyone!!! so my friend has a 4.0L '90 XJ that just wont stay on.It was running fine with no problems and then it just didnt turn on. It seems to want to and it does...... every once in a while, but then it turns off after blipping the throttle or after idling for a while. We noticed that it would turn on after disconnecting the MAP sensor so we tried replacing it but it still does the same thing. There is a nice healthy spark and fuel at the rail but have not checked if the injectors are opening, although I do get a strong smell of unburnt fuel from the tale pipe. What can cause the injectors to not open? Is it possible to have an intermittent CPS problem since that seems to be the most popular no start prob? Anybody know the proper ohm readings for the CPS ,TPS or fuel ballast resistor?

Thank you guys!!

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

here ya go... TPS ISM O2 MAP all in one doc with pics.

Thank You!!!