Hi, good questions.
I believe it's a Bosch sensor. It is a direct fit. It's the front sensor that I replaced, and the front sensor is the one I unplugged.
I haven't done any testing on the wires yet. Between which points should I test?
I do have fairly fresh plugs, wires, cap, and rotor. I also have new injectors, new crankshaft position sensor, new TPS, new MAP sensor, clean IAC, clean air filter, new cat (magnaflow catback), etc. The motor makes good power at full throttle throughout the RPM range. The odometer reads around 240k miles, and it's a 1999 XJ 4x4 with NP242, AW4, 8.25 rear end, and a rubicon express 3.5" lift with new spring packs and xfer case drop.
I recently replaced the motor mounts and exhaust manifold, which was severely cracked. I was hopeful that the new manifold would fix this problem but it did not. Although it runs a lot better now, it has become harder to start on a hot start.
Have not tested fuel pressure, because I don't have that equipment, but I don't suspect the fuel pump since it's clearly able to deliver adequate fuel flow under full throttle.
One other issue that I'm a little concerned about is the wiring to the camshaft position sensor in the distributor. Two of the wires leading into the plug on the harness side are exposed and there's nothing stopping them from shorting to each other. However, they are physically separated at this time and I would hope that I'd get a code if they were indeed shorted. I'm a little reluctant to deal with the issue because the only way to fix it I can think of would be to cut the harness and splice in new wires.
I've been seeing around 13 mpg on average, up to 18 mpg at best.