95' 300cid runs wide open

Hi! I'm new to the forum and hoped somebody out there could help me.

I have a 95 F150 with a 300ci 6-cylinder, FI.

I needed to replace the valve cover gasket because of a bad leak.
I started by taking the intake manifold and the various all the parts connected, etc.

I thought I put everything back the way it was, but when I started it up, it went up to about 4000 RPM and stayed there.

The throttle isn't stuck open. I blocked off both air intake barrels on the throttle body, and it still started up and ran wide open. The throttle plates in the throttle body are closed and I dont see any leaks in the manifold.

Anybody got any ideas as to what I missed?

Im in High School and need to get to my summer school classes!

did you put the idle speed control valve on backwards?this could cause the engine to run at that speed.