1998 Nissan Pathfinder Hesitation/Missing when in drive and

My 1998 Pathfinder wouldn't start one morning so I had it towed to service station where they performed diagnostics indicating that I need a new distributor rotor and cap and 6 spark plugs. When I picked up my vehicle, I noticed that when idling in drive (like at a stoplight), it hesitates or misses every few seconds until I start accelerating/moving again (but never actually stalls). When I look under the hood, the mechanic and I can see and feel it sort of jump when it's doing this. After checking their previous work done and finding no problems or cracked spark plugs, mechanic wants to put in new spark wires because they weren't done or suggested when new spark plugs were put in originally (2 weeks ago) and blow out injectors. But I am being told that even after them doing this and spending an additional $500+ that this may not fix the hesitating/missing problem because they don't know why it's doing it but that it's probably not hurting my vehicle should it continue to run this way if no engine or service lights are coming on in my dash. Am I wasting my $ on these additional services? Thanks.