Idle racing when warmed up.

[6PakFish]

I've been chasing an idle issue. When the car is up to temp I loose the idle. When cold it idles at 750 to 800 rpm in neutral. When it gets to 190 it will idle at 1500 to 1700. If I sit at a long light it will drop down to 500 until I tap the throttle it will jump back up. I have checked for leaks and if the butterflies are open but they are closed. I'm running a summit 750 with vac 2nd. I have a fuel regulator with a liquid filled pressure gauge. I have noticed that the pressure gauge drops to about three psi when warm. Not sure if its the gauge or fuel pump. I have read that those gauges tend to drop when hot. It runs 7psi when cold. I have changed the regulator and filter too.

[nqkjw]

I reckon your mixture screws are too rich.
When your idles drops after a long wait at lights is your plugs fouling.
A couple of hints.
If it idles when it's cold it's too rich.That's what fast idle solenoids,chokes and fast idle cams are for.
To set your mixtures you should do it hot.
Have an accurate tach hooked up(I use a digital tach readout on a timing light)and adjust your mixtures to max rpm while your setting your desired idle rpm.
When you have the max rpm at idle,then lean it off enough to drop abt 20rpm.
This is referred to as "lean best idle" and prevents plugs from fouling due to extended idling.

[Changin Gears]

This problem is usually caused by timing, the the mechanical advance kicks in and causes the idle to increase.

[6PakFish]

This problem is usually caused by timing, the the mechanical advance kicks in and causes the idle to increase.

So how do I go about fix'n it. New springs?

[6PakFish]

I reckon your mixture screws are too rich.
When your idles drops after a long wait at lights is your plugs fouling.
A couple of hints.

It's not fouling out the plugs, and it idles fine after it comes off choke.

[Chryco Psycho]

This problem is usually caused by timing, the the mechanical advance kicks in and causes the idle to increase.

This was my first thought too , but it coul dbe a number of things , often the idle increases a little when warm & this can tkae it over the hump & advance the mechanical advance , siffer springs or a spring without the long loop end can change the curve enough to keep things steady