95 GMC Yukon Problems with misfiring while idling

gmc
yukon

#1

I have a 95 GMC Yukon 2 W D, 5.7 V8. The problem is that the engine has a misfire while idling. The RPM will drop some then come back up like it wants to die sometimes. As far as driving the vehicle it drives perfect, it only has a problem when it’s idling. It will idle fine for a few minutes then misfire a little bit. I have replaced the computer, distributor, plug wires, and plugs, as well as setting the timing back a little bit and it helped some but still has a little breakdown idling sometimes. Does anyone have ideas as to what else could be the problem? I think it’s the firing, not the idling as the problem. Thanks for any feedback.