1993 Chevy Camaro Starting problem

Engine Performance problem
1993 Chevy Camaro V8 Two Wheel Drive Manual 60.000 miles

I have Camaro Z28 1993, the car start good with cold engine, and with hot engine. But when I leave the car to cool down 25-30 min. After drive. It wont start without throttle. I can start the car only with full throttle. Some time when its very cold outside the car start, but work in very low rpm. 400-500, its go to normal rpm after few min.
I think it is maybe a fuel pressure problem. I will check the fuel pressure, but I don`t now how fast has the pressure go down when is everything ok. In the system?

For example, from normal 41.0 - 47.0 psi to 31.0 - 37.0 psi (10psi down), how long have to wait 5-10min, 15 min of more?

Best regards,
Zoltan Mak