Chevrolet Repair: engine, chevy silverado, air control valve

Question
Hello,i have 1991 chevy silverado 5.7 liter throttle body 4 speed automatic with 85,000 miles.The problem is on cold start ups it has to turn over several more times than normal to start then when it does the idle go's up and down and up and down almost to the point that engine stalls and then when i drive it it spits and sputters and misses until it warms up then it improves but idle still go's up and down.Also when i shut it off at running temp and wait 15 to 20 minutes then start it the idle comes up then drops and engine will die then i can restart it and it will stay running.Would very much appreciate any suggestions you may have.Thank you for your time.Dave.

Answer
Hi David,
Possibly the idle air control valve in the throttle body just needs cleaned....can do it without even removing it probably.
A vacuum leak could also cause that, so clean the EGR valve.
And I would also want to test the fuel pressure.

Van