1996 GL 3.8L Idle/stall/rpm issues

[gammynet]

Idles rough Sometimes when starting. Rpms, on a count of seven (and I have counted) will jump from 700 to 1200 as an example whether running or at idle. Recently started stalling when at low speed as in backing up, or letting the motor pull me forward in a line up and this morning when I was slowing for a stop light. Starts again like a dream and off I go. Plugs, wires, egr sensor, ignition coil have been changed. And the weird thing, it comes up 305 or AC on every check, before, during and after. No electrical issues. Gas mileage is okay. The engine light is as consistent as the rpm issue - rough idle- blinking-drive 10 feet light goes steady and again weird, today it went out on its own, which is a first. I love this ol girl, help me please.

[tomj76]

Check for vacuum leaks. The PCV hose is a likely failure point. Also take a look at the IAC that it isn't going crazy. Of course make sure you have good plugs and wires. A lower priority would be the EGR ports under the upper intake manifold.

Do you have misfire codes? Do you have a scan tool to check the fuel trims?

[gammynet]

Thank you for getting back to me. Smoke tests done, no leaks. Plugs and wires are good, spark test also done. Codes are just as mystifying, keep changing. IAC is next. EGR ports. Maybe lower manifold gasket? Yesterday ran like a charm, no issues whatsoever. This backyard mechanic'ing in winter, when you don't know what you're doing is getting old. But I will prevail! Fingers crossed it is before it drops to -40 again.
Maybe a $2 fix? clean fuel injectors? I will be happy but pissed if it works.

[tomj76]

Another thought is fuel pressure regulation. If the pressure isn't maintained (especially if it drops too low), then stalling could occur. However, on first glance I'd also expect some fuel issues during acceleration, since the fuel demand in those situations would be likely to cause even further drop in pressure.