Our '93 Escort 1.9L with 98K miles has had the check engine light on for a
while. The memory codes scanned 122 (TPS signal low) and 172 (running lean).
I cleaned the TPS connector and reset the codes. That seems to have fixed
the code 122, but the code 172 keeps coming back within ten miles of driving
(three times so far).

I assume that checking the fuel pressure will be the next step. Can someone
advise me where I can buy a Schrader to 1/8NPT adapter to connect my
pressure guage to the fuel line? Beyond that, I can imagine cleaning the
fuel injectors and checking more carefully for vacuum leaks.

But I have a suspicion that I'm taking the code too literally. Is it likely
to be a falty sensor mimicking lean conditions? Are there any inexpensive
parts that I should change as a shot in the dark?

Your advice as to how to proceed with the diagnosis will be appreciated.

TIA,
Blake