Check the valve on the intake manifold. Carbon likes to build up and get these valves stickey. Try giving the valve 12 volts across the two terminals and see if it moves. It should move freeley. If the valve moves freeley try measuring the voltage at the valve. About 5 volts is normal. No voltage and you should start with the fuse. If the fuse is good sometimes the wires between the valve and the computer are bad. Check the wires out. Good luck. John