I am at my wits end.1996 1500 4x4 5.0 with 183k. Problem started with a hesitation at about 2000 rpm's on freeway accelarating after a de-cell.Thought bad gas,did gas dry,injector cleaner.No good.went to fuel filter,had to cut splice lines,no good.tried fuel pressure regulator, no good.Finally bit bullet,took to local hack and said fuel pressure good at 65psi,NO CODES and allegedly cleaned and checked map sensor.Suggested injectors and possibly timing chain.His scanner was reading lean under load and timing up into the 30 degree marks.Said injectors for sure first 1300$ did them myself,all went easy and quick(half price too) I put new injectors in yesterday,still not fixed.Ive noticed a few things 1. tach twitches and drops like crazy when it happens 2.hesitaton from stop seems like getting worse3. and although alternator is new and was just checked to be good,my volt gauge which has read 14 for 9 yrs is down 2 lines,thinking 12.5-13+/-??
in the morn on start up its right at 14+. Could this be distributer related? sensor? voltage? Im completely lost and throwing parts at it now.Could use some help.....please I beg of you!

 

Your milage doesnt justify needing a timing chain. No codes so sensors are probably working ok.
Remove battery have it tested. If its ok,
take a 3/8 bolt thead it into terminal. take small punch and small hammer and tap at the battery terminals to fill in any old groves made in the lead by battery cable. clean battery and cable surfaces with wire brush. Check that belt is not glazed and that the belt tensioner spring is ok.

I had same issue, mostly when passing. the computers are voltage sensitive.

You can also inspect the injectors by watching them work at ide and while reving it up a bit they should not ever drip especially at idle if they do they are dirty or beat.
always replace distributor rotor. Cap can be scraped. factory plugs last almost for ever