my 88 4.0 wont start inless u pure fuel in the intake that is the only way it will stay runnin. so i'm guessin that my injectors r not workin but they r new i'm gettin good fuel pressure all the way to the fuel rail so was wonderin if it could be a sensor i also just replace crank sensor and its gettin good fire to all plugs

 

Do you have a power probe or multimeter? Check for power to your injectors. Power Probe would be the easiest thing to use if you can get a hold of one. And check ground to, b/c if you're getting fuel pressure and spark, but no spray from any of the injectors, they share a common ground, but are individually powered by the ecu.

 

Here's a wiring diagram of your renix engine controls