99 xj
got an error code p0193
Fuel Rail Pressure Sensor Circuit High
​​​​not finding much info for the xj
not sure if I'm looking for a sensor or maybe fuel pressure regulator
my symptoms are rough idle from cold start like its almost about to die on me but hasn't yet
also sometimes when I put it in to park or neutral the engine will Rev up to 2000 rpm and then back down then back up to 2000 back an forth till I pUT it back into gear.

could be related
Any experience?

 

I would start with some basic fuel system testing. Get a fuel pressure gauge, they can be rented at many parts stores. The fuel pressure spec for the 99 is 49 psi, plus or minus 5 psi.

Here is a link to more on this code, which is very rare for an XJ. It may be an electrical issue as I am not aware of an actual fuel pressure sensor on the 4.0 liter engine. You're positive it's a P0193? I'd double check to be sure.

https://repairpal.com/obd-ii-code-p0193

 

Cool,
I'll get on that pressure gage,
if the pressure is too low or high what would be the next action?
I guess if the pressure is where it needs to be that would make it an electrical problem?