Bucking Metro

I have a 91 geo metro Fuel injected 1 liter. When I take off from a stop the car rev's up and down about four times and then goes. Seems like it has to be at low rpm to get this pulsing. With air cleanr off if I look into the TBI I can see the fuel being sprayed then it stops then starts again. Any Ideas for this problem?
thanks
Alpa

there is a solenoid on the rear of the intake below the throttle body next to the firewall. has a vacuum hose the goes to the side of the throttle body. take the hose off the solenoid and put something in it so you don't have a vacuum leak into side of throttle body and see if it fixes the problem. if you does your solenoid is probably bad or sticking, can leave hose plugged or find another solenoid

Thanks Ill give it a try.