95 astro code 21 and 45

95 astro with 190,000 miles runs terrible feels like it is pushing all the time when break is applied. ck'd codes and concluded the code 21 is causing the code 45. haynes manual says to ck out TPS i did and it failed bought new one, no change thought new one was bad swapped it out for a 3rd one same thing manual says .5 vdc output at idle I'm getting 4.8vdc at idle with all 3 TPS sensors also gas milage is between 15 and 16 MPG HELP PLEASE

Make sure you Check the voltage on the output wire.
And make sure ground wire it is grounded.
Open tbi and check and see if voltage changes.
5 volts ref is the input to it.

INPUT VOLTAGE IS 5 VOLTS
gnd is good
the voltage does increase to 4.96 when throttle is increased
if connector is removed output voltage drops to 0
could i have gotten 2 bad tps sensors from autozone?
what would be the resistance of the sensor be if tested off the van?

Out put voltage should be .5 to 1.0 volts closed throttle.
And should increase gradually with no drop outs opening throttle to 4.5 to 5.0 volts wide open.
Hard to test off but resistance should change when you move it.
And the only true test on a TPS sensor is with a lab scope that will show any drop outs or glitzes.
Factory OEM parts only hurt one time.
Cheap Aftermarket parts can bite you in the rear many times.
And sometimes dealer parts have a better price tag than aftermarket.
If AZ had a bad sensor the next one you get will be out of the same batch or the hole batch may be bad.
Go to the dealer or another parts place and get one.

POINT MADE
but if the auto makers would price their replacement parts more reasonably then more people would purchase OEM parts instead of going to the aftermarket
I would pay more for OEM but not double the aftermarket
GM TPS 55 bucks
i can't afford that and most people can't, that's why we are DIY'ers
thank's for the help
I'll post more info when I get it fixed