I have a 94 gmc vortec 6 4.3 truck started running rough and stalling and would not idle without surging. thought of gas problem changed fuel filter added seafoam to gas . still same problem only worse. truck has 234,000mi. has always ran great. help

 

Sounds like you have a vacum leak. Get some starting fluid and spray around the intake to see if the idle goes up when you do. Try to pin point the area.

 

I will bet , fuel pump . Need to check fuel pressure , should be 60 to 65 psi
Any drop in fuel pressure will not run right. Also fuel regulator could be bad
see if you see any leaks , around it.

 

Had the same thing on my '90. EGR Valve was stuck wide open (carbon) Ran o.k. on the highway but just like yours at lower idle.

 

thanks for help. but i have found another problem.injectors flooding engine.wont idle or stay running to much gas.help

 

i think i have found the problem. fuel pressure regulator bad . thanks for the help.im just and old shade tree mech. dont know much aboyt theses new veh.i hope this dose it.

 

Hope you found the problem. Mine was flooding so bad your eyes would tear up in the garage. Once I took the EGR off and knocked out the carbon, manually cloced it. Put it back on and left the hose undone till I bought a new one. Good as new!

 

replaced fuel pressure reg ran perfect for about 30 miles almost didnt make it back to house.same old problem any body got any good news,need help

 

Hey, don't mean to sound like a broken record, but check the EGR. Take it off (should be on the passenger side of the intake manifold. two bolts and a hose to remove) Tap it on the bench, I bet a bunch of carbon falls out. Check the shaft that works the diapragm. If its shiny, its open. Use penetrating oil to get it closed. If you get it closed, reinstall, but don't hook up the hose. Start it up. It should run perfect, if its what I think it is.

 

thanks ill check the EGR this old man has got to get some sleep.