Strange sensor 740 2.0 gl

Just a guess. Is this the microswitch which is switched off when the throttle is closed. If so it is adjustable with 2 screw bolts on the side. Sends signal to ECU to advance retatd ignition etc.

Sounds like thats it. would this effect the fuel economy?

Affects a lot...cant remember exactly what it controls but I think that it affects the ignition timing. From memory the switch has to be closed during ignition timing. You can check it the switch is working with a meter or simply by using a torch battery and bulb. Mt Haynes says that the switch should open just as the throttle opens. Often during basic services this is not checked and the throttle switch is open when the ignition timing is done. Adjustment..2 small screws...adjust so that a click is heard just as throttle is opened. Must affect fuel consumption if not adjusted properly as the ignition timing wont be correct. If you have the original handbook check the timing for your car...mine was 5 degrees yet all other models were 12. Even the dealer got it wrong!!!!