I finally learned to pull obd1 codes and currently have two tps codes.
I replaced tps last year and truck ran way better but still every so often it cuts out/chugs.
So I tested DC voltage and it's way out of wack!
(used some youtube and found a good informational video)
I enlarged mounting holes on the tps and could only get to .65V.
I discovered the tps dosent have a shim and to get to .96 - .99V the tps can't be mounted due to being nearly 1/4 turn off, I tried flipping it and the lowest I could get was 1.4V.

So my questions are

1.) Do I need the shim or can I use an O-ring?

2.) Why would the tps alignment be so far off from mounting holes?

3.) Should I just buy a new tps now since the shaft blade most likely has been slipping on the plastic tangs for the past year?

 

You need the shim
Get a new TP sensor

 

I would first start by making sure its installed properly and is properly engaged with the roll pin on the throttle shaft.. Disconnect the TPS and connect an ohm meter to the wiper of the TPS and one of the other leads. Work the throttle and see if the resistance changes as you move the throttle.

If the TPS holes are not slotted it requires no adjustment and should not need shimming or drilling..Shimming or drilling the mounting holes is just masking a problem. I would make sure the source voltage (12v) to the TPS is correct and the other lead is connected to a good ground. If that checks, try an OEM (Motorcraft) TPS sensor. .

 

Agreed, slotting the bolt holes of the TP sensor is not advised
The old ones had a throttle shaft with a roll pin, most of the new ones have a screwdriver male slot
IF you cannot get the idle TPS to .8-1.3v there is a problem
That source voltage to the TP is VREF 5 volts