Jeep Repair: 98 GCL 4.0 Engine Miss All RPMs, old timer, backup light

Question
QUESTION: I almost hate to ask but how can I isolate an engine miss that I can feel at idle and driving down the road. It isn't constant but occurs 90% of the time. I have a good mechanic (old timer) but he didn't detect it so he didn't try to find it. It has been missing for about the past 2,000 miles. I can see the tach drop a bit when it misses at idle and now a couple of times the miss has actually turned into rough running at idle or slowly accelerating. The plugs were just replaced to see if that was the cause and because they had 140,000 miles on them.  I have had some fast idles when I shouldn't (no reason for the auto choke to have been activated but it seemed to be). I actually heard a pop/misfire/stutter/cough once after sitting in traffic a while and then moving away from a stop.
Not related but is there access to the fuel pump without dropping the tank and is there a way to adjust anything so my backup lights will work when in reverse?
TIA,
Skipping and getting worse!

ANSWER: if there is a miss then a scanner will be able to see it  and one which cly it is on.

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QUESTION: Thanks.If I wanted to invest in a scanner do you have a suggestion? I own multiple vehicles and brands. Do you have an answer about access to the fuel pump and answer about the backup light adjustments?

Answer
u will spend about 1000 or more for a good enough scanner that will read all the stuff  that would be needed  plus  U would need to know what u are looking at with the sensors in order to see if they are in range  and so on.

the fuel pump is in the gas tank  it would need to come down  and there is not a back up light adjustment