Poor 5.9 v8 performance

[Blawson117]

I've got a 98 1500 with the gas 5.9 it has 139,300 miles. I started it up to go home one day from work and it just ran like crap. It has bad acceleration and pops and backfires sometimes. It shakes and vibrates while driving but gets really bad once it kicks into overdrive around 40 mph and up. I know it's got a vacuum leak because that bundle of lines by the fire wall are all cut. It does hiss and idle rough after a few minutes from the leak but it's been doing that for about 2 months since I got it. This is just bizarre to me. I was thinking it's a rod getting ready to throw its self but I'm not sure.

 

[PowerWagonAZ]

Sounds like it could be a bad fuel pump.

 

[Blawson117]

So started it up yesterday to go to the auto store and now it runs fine besides the vacuum leak but the poor performance issue is gone, is it possible for the fuel pump to be an intermittent issue or would it just go out and stay out

 

[dapepper9]

More likely it needs a tube up and plenum job. Plugs, wires, cap, rotor.

 

[94ram1500]

that defiantly sounds like a vacuum leak