Strange codes on 98 cherokee

My 98 5.9 grand cherokee started acting odd yesterday. Occasionally,
from a stop it would be real sluggish about taking off and sounded a
bit odd...almost like it wasn't getting enough gas. Then it drove ok
for a while, shut it off and started it back up. CE light was on so I
pulled the codes. I got these:

PO726 The PCM has detected that the voltage signal from the engine
speed input is out of range for the current engine operating
conditions.

And:

P1281 Injection control pressure out of range high.

Any ideas?

Never came acroos anything that involved before, usually simple stuff
that I can diagnose right away, but I'm kind of aprehensive about
driving it without knowing what's going on.

Any help is GREATLY appreciated.
TIA

Mikhail

 

are u running the recommended premium gas for that jeep with the 5.9and
when was the last time you changed the fuel filter???

 

Yes, and about 3 months ago

 

First, find a new source for code descriptions. P1281 means the
engine coolant temp is cold too long. Usually a thermostat, but a bad
ECT sensor could cause it also.

P0726 would be a trans related code, and if it was causing the trans
to go into limp-in mode, would explain the poor performance.