[Shotimes] HEGO sensor trouble codes

[Thesing, Hunter M.]

I talked to a Ford technician yesterday about a stalling problem and HEGO
trouble codes (17*s).  He thought that my sensors were bad (aftermarket
Bosch-1month old) and weren't switching fast enough, since the codes are for
reading lean and rich.  He suggested getting Motorcraft ones instead.
According to him, he's seen this several times when aftermarket sensors are
used.  Any thoughts?

Hunter Thesing
'93 MTX EG
K&N Air filter