Just the past few days, my '94 GC Laredo with a 5.2 V-8 has been idling roughly when it's warmed up, the air conditioning is running and it's hot outside.
If I pull into a store parking lot and put the trans in Park and shut off the A/C, the idle will shoot up to exactly 1500 rpms for 3 or 4 seconds, then drop down suddenly and the engines tries to die. It normally idles and purrs like a spoiled kitten, because it is, from the new water pump and injectors to regular tune-ups and oil changes, clean air throttle bodies and butterflies, etc.
Fresh gas in the tank 3 times since it started doing this.
Again, it idles smoothly at 750 rpms until I drive it with the A/C on for a while, then it idles roughly when I stop at a stop sign or red light and tries to die. If I shut off the air while sitting there idling roughly, the idle shoots up to exactly 1500 rpms for 3 or 4 seconds, then tries to die.
The truck starts right back up if it does die. It's not stranding me anywhere, so I doubt it's anything serious.
Anyone have a quick check list of sensors, tips, hints before I tear into it blindly?