2000 Jeep Cherokee Intermittant Starting issue has escalate

2000 Jeep Grand Cherokee Limited
4.7 L Power Tech
All Wheel Drive
It’s probably been a year since I talked to you about the intermittent starting issues I was having with my Jeep. I was convinced that the problem was the result of a fuel pump failure. After purchasing a new pump, my mechanic told me there was no reason to install it because my fuel pressure and pump were fine. When I brought it in last, they claim that no error codes were being produced by the computer. Shortly after I picked it up, the check engine light came on but it continued to run fine. Occasionally, the jeep’s symptoms would return (maybe 1 in every 50-75 starts) but after waiting a few minutes, the engine would fire right up so I paid little attention to it. A few months ago I noticed an ever so slight noise coming from the engine that I had not noticed before. The best I can describe it as is a faint chirp sound almost with a hint of the sound of slight vacuum pressure. The most interesting thing about this noise is that it continues for a second after the ignition is turned off. I first noticed the sound when I parked in the garage, turned the engine off and heard it when I jumped out of the truck. After noticing it, I cranked it back up and could hear the faint chirp, ping, suck noise.
I’ve been researching the symptoms and asking around a couple people have mentioned two sensor issues on Jeep Grand Cherokees that have been problematic: crankshaft position sensor and/or camshaft position sensor. I’ve located them on my engine but I can’t justify digging around and replacing them when I really don’t know for sure if either of them are causing the problem.
Does my rambling bring any ideas to your mind? Any advice you can share would be much appreciated. Btw: the jeep last started 2 weeks ago. I’ve made approximately 10 attempts to crank. It turns over but acts as though there is either no fire or no fuel. I’ve read that a bad crank sensor will disable the vehicle?
Anyway, let me know what you think. I’m guessing I should probably just take it to a jeep dealership at this point to see what the computer is saying now that it won’t start at all.