under acceleration, in any gear, it has started to stumble and stall. I changed the cap and rotor, wires, checked the plugs as they only had 8,000 on them, the oxygen-sensor and a new fuel filter. I can still feel the serge and under flat out acceleration it still stumbles. I thought sure it was the oxygen sensor as that is the sourse of most tune-up problems I have had. The motor has 115,000. Any suggestions?

 

I had a similar problem. Turned out the catalytic converter was blocked enough it was causing problems with the EGR system. Have the EGR checked. If it checks good, then check into the cat. I made the mistake of ordering the high dollar cat that is a direct fit. I ended up at the muffler shop anyway to have them adjust the connection to the headers. A universal fit is much less expensive and just as good. Dynomax sells a high flow cat under the Walker name. I also believe Magnaflow has a high flow cat.

chevyblues

 

Check fuel psi.....spec is 9-13psi but optimal performance is found at 11-13psi...

 

My 1992 5.7 was doing same thing 2 weeks ago. New plug wires solved my my loss of power. Hope this helps