Most of what you buy that is not from one of the recommended dealers is Chicom junk especially electrical parts.
What model truck do you have?
Do you have the 400A alt? (that's where the tach signal comes from)
The higher the voltage is compared to what it should be tells the trans that the throttle is advanced farther (more load etc) than it is so it will shift late, try to fudge it to around .45-.5v at idle while you wait for a real TPS to arrive.
HPG has them on sale.
www.hummerpartsguy.com
They only have 2 in stock of the part # 5743243 if that is the one you require.
I have no affiliation with HPG