My GPX had been off the road for a year as I was out of the country. During this time, it had a new battery and was started up and run (but not driven) every month. I now am back in the country and wanted to get back on the road with it, but it now cuts out whenever I take my foot off the accelerator. The car was started and driven around for 10 minutes without a problem. I stopped for petrol and it was then that the engine would not stay running if I took my foot off the accelerator! It still starts and runs but only if the accelerator is pressed. I tried to increase idling speed with the screw on the top of the throttle body to no avail, but noticed the throttle cable was very slack. If the cable is held taut the engine starts and runs fine. Can I adjust the throttle stop screw to hold the throttle slightly open to rectify the problem?? I've read this problem could be caused by the stepper motor, but could it simply be a problem with the throttle cable? Can anyone offer any advice please?

If the throttle cable has too much slack, it won't stay open at light throttle, therefore cutting air off to the engine.