I have a 350 in my 78. I set the timing at 4° BTDC. My rpms are about about 1100. Sometimes the throttle will stick closer to 1500 but a tap of the pedal fixs that. I have the idle screw all the way out.

Is something set in the carb that is preventing the throttle from closing just a little.

 

You need to adjust your fast idle screw out a little. It's on the passenger side of the carb, part of the choke linkage. Since tapping the throttle drops the fast idle, it also sounds like your choke might not be opening up quite all the way (if the choke is working at all). Take a look at the choke butterfly when the engine is cold, it should be shut. When hot, it should be open vertical. What carb do you have?

 

I forgot the model but it's an edelbrock 4bbl with electric choke, it's the fed version of the california street model (no fuel vapor return). I rebuilt it, I must have missed something. The butterfly is vertical. I looked on the pass side yesterday, no screws but I believe I found it on the drivers side. It pushes on the rod that goes to the pass side.

 

Here's some great video help for Edelbrocks. Check out the carb tuning videos. Also make sure you have all the unused ports plugged!
Edelbrock.com - Tech Center - Carburetor Installation and Tech Videos