My car is a 350sbc, with a 4bbl holley carb. My car idles at 1500 rpms, give it gas and it shoots up then comes down to 2000 rpms and then slowly drops back down to 1500. The car usually idles at 1500 for a while sometimes goes to 1600-1700. I have tried tuning the carb and if i turn it about 4.5 to 5 turns out it will drop to about 1100-1000 rpms but then it sounds like it wants to die. So i turn the car off and try to turn it back on and it will not start at all. Turn the screws all the way back in and it starts right up again. So if i turn the screws out all it does it raise the idle. And by moving them out i mean turning them counter clock wise. I can not for the life of me figure out why it idles so high. The car has an after market CTS. Could the cause the car to idle so high?

The CTS only affects the computer, and your Holley isn't controlled by the computer (and the computer doesn't directly set the idle on computer controlled carbs). But, you probably have an aftermarket temp gauge sender, anyway, but that still won't affect idle speed.

Start by disconnecting the throttle cables and see if the problem persists. If not, you've got an issue with one of the throttle cable holding the throttle arm open.

Next, check your choke operation. It should be fully open when the engine is warm (you didn't say if you have a manual or electric choke).

If the problem persists, read the Holley carb tuning sticky in the top section of this forum. If, after you go through all those steps, you still have a problem, come back in.

Its an electric choke.

The factory electric choke used a single wire, 12 volt positive. Most (at least, every one I've seen) aftermarket electric choke thermostats have a power and a ground terminal - you need to hook up the factory power wire to one of the terminals, and run a wire to a ground from the other. Is that how yours is done?

It has a single 12 volt wire.

Well my idle was down to about 800-900 turn the car off and turn it back on and didnt change, come back the next day and back to 1500 it goes.