99 xlt 4.0 pos

[jhknight56072]

this 99 is in fair shape with 180,000 miles on second engine.. first one had a bad valve seal and resulting damage.
For years this engine wants to run / idle rough most of the time. when taken to a shop they have replaced a cam position sensor, spark plugs-several times, spark plug wires. any cure seems like it was coincidental maybe? I replaced the coil pack which needed done anyway due to damaged plug in and rust. no difference.
this time took it to Advance Auto and had them plug in, we got a misfire(no shit) in cyl #5 with possible vacuum leak. (don't remember the exact code) The check engine light went out and ran fair for a couple weeks then back to bouncin. recurring intermittent rough idle.
I did remove #5 plug and it looks fine. Tail pipe is clean enough to eat out of so I'd say running lean? I tried sea foam in fuel and carb cleaner on intake sensors and intake. nothing. yesterday just started briefly to move it out of the garage and back in. today it runs like sh*t. again.
so where do I go from here? tired of taking it to shops that know next to nothing about these old systems and shelling out for spark plugs every 5k miles. help!

 

[Curious Hound]

Could be a problem with an injector. Need to check voltage to injectors and the firing of them.

Need to fix the vacuum leak. That can cause rough running.

Need to check compression.

Maybe even a problem with the coil. I think there's a way to swap 2 spark plug wires at the coil and see if the problem moves to the other cylinder. But I'm not sure which 2 wires to swap