High REVS in Port-Fuel-Injection

Hello, I have a 1986 Oldsmobile Delta88, 3.8L, V6, port fuel injection.

I posted earlier that my fuel economy has gone down very noticeably.

One thing is that i notice that the revs are really high. Sometimes specially when it was just started it will run at

What would cause a Port Fuel Injected engine to run too high rev, specially at start up?

This things can not be adjusted in this cars. So what could cause it?

Thanks!

Myc1972