I’ve been through it all w/my 99 Cherokee lately (155K mi). I recently had similar problems, and I probed the fuel system first on this one as well by swapping relays (under hood, passenger side), so I think T&R gave good advice on this one.
I thought my $11.56 solution was it until the occasional stalling started occurring. If you strike out in the fuel department, you might try replacing your crankshaft position sensor (CPS). Typical problem in these vehicles with this mileage. One of the problems is that a failing CPS will often not show up in the diagnostic codes.
The CPS is located on the bellhousing just behind where it mounts to the back of the engine at the 1 o’clock position as viewed from the front of the vehicle. It’s secured by 2 bolts, and while not a difficult repair, the sensor and bolts are difficult to get to. The sensor is usually about $90 or so. A potentially expensive repair if you don’t tackle it yourself. You’ll need about 18" or so of socket extensions to reach the bolts from beneath the vehicle.
I just installed a new one last week. It took 1.5 hours, and completely solved my problems. A great candidate for Stump The Chumps!