pshpshmuthafuka420

my car has a really jumpy idle and I have been trying to get better gas mileage out of my car and tune it properly, well I have adjusted my TPS to spec using the voltmeter method and the idle is consistant but then when I start driving it goes back to out of spec. am I missing something or whats going on, my SAFCII also registers my TPS as functional so I dont think it could be bad. any other suggestions would be appreciated.

*I also need some tips on timing 13bt's since I have never done it before, the FSM's procedure is to vague to understand in detail.

Thanks