tahoe.mkIII
...
Might want to check the ignition switch, had a similar issue with the 2500. The key was worn out and would not engage the switch sometimes. Had to push the key in quite hard to get it to engage the switch. Occasionally it would disengage while driving, all the gauges will die/drop to the off position and the trans will go into limp mode. I had to pull over, shut it off, and slam the key into the ignition to get it to contact again. New ignition cylinder and switch and it's all good now.
Also possible ignition control module, I haven't replaced one of those in a long time, but I recall the old 88 had some similar issues that were solved by replacing the module.
Also possible ignition control module, I haven't replaced one of those in a long time, but I recall the old 88 had some similar issues that were solved by replacing the module.