My '99 F150 4.6 Off-Road with 184k miles is a smooth runner most of the time, and it's been an OUTSTANDING truck. It's plugs were replaced at 100K and had all the necessary fluid changes regularly, and really hasn't been a problem prone vehicle until just very recently. I know it's going to be due again for plugs and most likely plug wires at 200K, but I'm wondering if those might be the culprit for my rough and inconsistant acceleration from a dead stop. It never back fires and it's never all the time, but the motor will seem to spit and sputter under acceleration up to about 2500-3000rpm before clearing right up and winding up to redline. Because it's sporadic, leaves me to believe it's not fuel, and the fuel filter was changed just a few hundred miles ago. I'd really like to drive the truck to 200K before replacing the plugs and wires IF they're not the real culprit. I don't want to simply start swapping parts until I find the problem, but would rather diagnose the problem accurately first and simply fix the problem the first time without spending a ton of money. So, with all that said, might there be ANY other items that I should be looking for??? Why does this only happen under acceleration and not while I'm cruising??? Does it matter that my passenger side manifold leaks due to one bolt head missing??? I'm really leaning toward just replacing my wires and plugs, but again, I'm trying to hold out and hold onto my cash if I can so I can R&R the manifold bolts...