03rubicon

I have a 98 Z71, 350 motor. I did a tune up within the last two years and after doing it the truck ran great and no longer was the truck hesitating-missing. Now last Sept while in Texas and pulling a small trailer and in overdrive it was doing it again but not to bad. Get home and forget about it for the most part. A week or so ago it started acting up again so for what ever reason I put it in 3rd and it ran fine. A few nights ago ( was raining ) it was missing while driving in OD, shifted into 3rd and it ran fine. Took it to a transmission shop, long story short they said nothing was wrong with the transmission but they did notice it missing. So they said it maybe bad plug wires or a cracked spark plug but if this is true wouldn't it miss all the time? took it out yesterday and today and it ran fine. Would appreciate any thoughts, thanks.

BAGnDRAG-K5

This sounds like a spark plug issue to me as well. However, if you have changed them (which should be done approx every 10k-15k miles) in the last few weeks, then look at the wires to see if any are touching anything such as each other, metal parts, see if they are broken or chaffed. This will cause them to ground out resulting in a misfire. The engines on these years of vehicles are not as efficient as the new ones and will need the plugs changed out with a shorter span then 100k like the new ones have.

The other part of this may be the torque converter lockup switch malfunctioning causing this reaction. If the switch is engaging and disengaging it could cause the hesitation/jerking action. This could also explain this happening so sporadically. I had a car that would do this (but much worse) as I came to a stop it flt like the clutch needed to be pushed (this was an automatic car). After I disconnected the four wire square plug from the side of the transmission, the problem was no longer present. Good luck.

Hope it helps.

OLD WRENCH

I too would think plug wires.When a part of the secondary ign breaks down it is worse under load. Mine started skipping while pulling a RV it would show up when starting out from a light. I replaced the cap,rotor,and wires and no more problem.

03rubicon

Thanks for the info, I do appreciate. There were some wires touching each other and one could have been touching the fire wall. Have moved the wires around some, hope this is as easy as that.

Cheezer61

my 97 did the same thing so if that dont fix it check the cap and rotor make sure that no moisture is getting in mine did i had a hairline crack in the underneath side of the distrubor so you may check that out to if the problem still occurs

shield1751

I have a 96 Suburban that has been very dependable. It has the 5.7 motor. This morning, I went out to start it, and it ran very rough, hesitating, etc. Once on the road, it stalled several times at lights. It runs fine under load, but it is not idling propertly. It also hesitates when you first give it gas. After about 3-4 miles of driving, the "service engine soon" light came on. It's the first time I've ever seen it come on. Plugging a code reader into it, I got no codes at all, which is very unusual, since I always had readings before. The exhaust also has a strong gas smell like it's running rich. Could it be the ECM/ECU starting to go....or could you point me in the right direction?

trevor.klassen@hotmail.com

SORRY but HEY guys I NEED HELP !!!!!!! I have a 1995 tahoe with a 350 tbi. It has 250,000 kms and it runs like crap. It runs better in park then once you put a load on the motor the truck tries to die. It runs alot better when cold and if your driving at higher speeds (thats if it can even get to like 80 kms), and you put the pedle to the ground it sometimes dies or will down shift and try and take off but wont go anywhere. I have un plugged the o2 sensor and no change in running, i have un plugged the knock sensor and no change in running. The EGR is new i have done the distributor, cap, rotor, plugs,wires, coil, tps, map, tbi gasket, checked the fuel pressure its at 7 psi,grinded down the grounds, timed it, checked for vaccum leaks, and it doesnt throw a code. If there is anything else i could try PLEASE let me know. thanks.