My 95 Sierra 1500 e/c ( 5.7 L, auto.,4x4) Tends to lope just above idle rpm, such as when driving through a parking lot slowly. Rpm varies between 600 & 800 rpm. If I plug the vacuum line to the EGR, the problem stops. I've replaced the EGR valve and solenoid valve, but the problem is still there. When coasting down hill, and throttle is almost closed, there is also a slight jerking motion. Idle is smooth, lots of power at higher speeds. All ignition parts (plugs, wires ,cap etc.) and fuel filter have been replaced.
TBI is bolted tight, and no leaks in vacuum lines. Anyone have any suggestions???? Thanks

My 95 Sierra 1500 e/c ( 5.7 L, auto.,4x4) Tends to lope just above idle rpm, such as when driving through a parking lot slowly. Rpm varies between 600 & 800 rpm. If I plug the vacuum line to the EGR, the problem stops. I've replaced the EGR valve and solenoid valve, but the problem is still there. When coasting down hill, and throttle is almost closed, there is also a slight jerking motion. Idle is smooth, lots of power at higher speeds. All ignition parts (plugs, wires ,cap etc.) and fuel filter have been replaced.
TBI is bolted tight, and no leaks in vacuum lines. Anyone have any suggestions???? Thanks

Herb, No suggestions but I to have the same problem ( 95 GMC 1500 TBI, 208K Miles) ...Here's what I have done ( and still have the problem)
1. New Fuel Pump
2. New Fuel Filter
3. New Injectors & Fuel Pressure regulator (300$ worth)
4. New Cat.Convertor & O2 Sensor
5. New plugs, Wires, Cap and Rotor
6. New Coil
7. New TBI to intake gasket
8. New vaccum lines (all)

PLEASE let me know if you find a Fix, I love this truck and want to keep it.

Thanks in advance
Ron

My truck kinda sputters and missfires through the rpm range and my problem is a bad MAF. Was running bad for a while then finally the idiot light came on so i took it to auto zone to get it scanned and thats what it showed, cheap fix $139 for a replacement but im gonna get a GMS aftermarket MAF.

My truck kinda sputters and missfires through the rpm range and my problem is a bad MAF. Was running bad for a while then finally the idiot light came on so i took it to auto zone to get it scanned and thats what it showed, cheap fix $139 for a replacement but im gonna get a GMS aftermarket MAF.

make sure old Cat Converter guts aren't clogging muffler.

GMC says they back their products, but i have a GMC built transmission that was had a gaurentee of 3 years or 60000 kms. their new warrenty is for 90000 kms.

i have just over 20000 kms on my trans and it kicked it. i maintain it as i should, and drive it in normal expected conditions.

i have contacted my local GMC dealer and they told me that they would not stand behind their work or their warrenty.

I recommend to all not to buy GMC products of any kind, they will leave you high and dry, with an empty wallet.

ps - No one told me GMC stood for Gimmie More Cash

MAP sensor (Manifold Pressure) has a tendancy to cause that problem, Especially on the old TBI engines.