I found it. I actually saw it before but this time I had a flashlight and looking inside through the little grille I could see what looks like a little thermistor. It all looked normal. I traced the wiring up to a connector lying next to the air cleaner so I unplugged and reconnected it in the hope that if there were a bad connection the movement might clean it up. I'll see if the ext temp updates quicker next time I drive.
Thanks for the help

OK, thanks I'll go out now and take a crawl underneath and look

Thanks for the replies. Piano guy, could you give me a little more help in locating the sensor? I'd like to at least inspect it and the wiring going to it. Should I be looking from underneath the car or down into the engine compartment with the hood open? And also what does the actual sensor look like?

On my 1994 LT1 coupe, the external temp display takes many minutes to update to the current outside temp once I leave the garage where the temp may be lower or higher than what's outside. Today for example, it was reading 82 when the outside temp was well above 90. I thought it had finally broke, but after maybe 12-15 minutes it updated to 92. Has anyone experienced this? And maybe found a fix.

Thanks for reading
Bob

I agree with 94hillbilly. I just fixed my 94 by replacing the vacuum check valve underneath the right fuel rail cover. It had pretty well disintegrated and was leaking badly. Good news it was less than $10 at Chevy dealer.