OK here's my problem i have a 1990 camaro rs and its has the 305 tbi motor i got my camaro back from a mechanic that set my timing to 8 degrees advanced sorry to say it did not like that so i took a timing light and set it to 4 degrees advanced and it seemed perfect but realized the temperature guage was not reading but was running fine till i took it on a thirty minute drive to the new job and it stalled for times on the way there and back what happens at that point is it starts to idle to low as it down shifting and then stalls but starts right back up no prob so got it home and tested cts,tpi sensor ,iac, end everything was fine with the wires all had the right voltage and sensor read normal so i pluged my scanner in and it told me code 23 intake manifold temperature too low so im stuck please help oh and sorry for this long post

 

Sounds like a vacuum leak.