Hesitation at highway speeds - 1999 Suburban

[texas_aggie]

I've got a 1999 Suburban 5.7L Vortec 4WD automatic transmission with 145k miles.

Lately, I've been experiencing a hesitation/skipping when at highway speeds and trying to accelerate past 65-70. Hard accelerations up to 60-70 aren't problematic, it's just the light pressing on the accelerator when I'm trying to maintaining the speed once on the highway. Even hard accelerations at 65 don't always cause problems.

At the recommendation of friends who have had similar problems, I've replaced the MAF, distributor cap & rotor button, and had the throttle body cleaned. None of this has helped the problem go away.

Spark plug wires appear to be new, and upon pre-purchase inspection the mechanic said the plugs looked good.

 

[Gatorboy]

Had a friend on here that told me those are symptoms of a stripped distributor gear. A relatively cheap and easy fix.

 

[texas_aggie]

After replacing the distributor cap & rotor button, it has gotten better. What would changing the distributor gear entail?

 

[Gatorboy]

It's possible that the cap and rotor will help some if they were worn anyway. I think the gear is around $40. Hardest part is pulling the distributor. If you have mechanical knowledge it's easy, but if not I'd take it to someone to have it checked on.

 

[Gatorboy]

Check out this link. One guy discusses seeing this problem on Vortec motors.
http://www.gmt400.com/forum/showthr...g-C1500-Only-at-Highway-Speeds-and-Under-Load

 

[texas_aggie]

So, just as simple as timing being out of whack? Or the distributor gear?

I don't have time to monkey around with this before our road trip to Mississippi and back (1200 miles, total) for Thanksgiving.

Any long term problems, or should I get this fixed now?

 

[DGA1]

Cheap and easy to check off the list would be a new fuel filter.

Blow throught the new filter to get a sense of how free flowing one needs to be. Do the same with the one you take off and compare the difference.

 

[Gatorboy]

The timing is only a TBI motor thing. The gear is on the newer Vortec motors. If you can live with it, you should be ok for now. It drove me insane until I fixed mine

 

[texas_aggie]

So, the truck ran great during my drive down to Mississippi for Thanksgiving. However, I noticed that the hesitation/stuttering goes away after about an hour or so on the interstate. I'm stumped. We'll see...

 

[Gatorboy]

Could be a fuel pressure thing