the voltage should be at .58 volts, with the throttle plates closed at curb idle, not on the fast idle cam or with the idle speed controller ram pushing the throttle open.
When you open the throttle wide open the value should be at 4.90 volts .
1.0 volts at wide open throttle is too low, not sure what is going on there.
Without enough throttle posisition sensor voltage , hitting wide open throttle will be somewhat lean, and shy on timing as RPM s build.
Also it may set a check engine light,as value may constantly be to low for engine rpms.
Fact is stranger than Fiction