"...i just tested between 16 and a ground on the frame. Was this substitution ok?" Wrong pin, frame ground probably ok.

Time out ! The FAQ procedure says ECU 13 to 5, NOT 16 to 5. but neither one applies to your '87 LH 2.2 ECT sensor. (13 is the LH 2.4 ECT/ECU terminal)

You could do the procedure from ECU, pin 2, which is the Blue wire I suggested that you probe at the firewall harness.

The ECU puts a nominal "reference" voltage (about 5 volts) thru that wire to the ECT. The colder it is, the lower it's resistance, thus more of the reference voltage will "bleed off" to ground. The ECU "translates" the drop in reference voltage to a drop in temperature.

The middle of the road (68 F) numbers are 2300 to 2700 ohms Resistance, which equates to about 2.2 volts (what's left of the original 5v reference voltage).
--
Bruce Young,
940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified--and going to be crushed unless...)
New 144 from '67 to '78
Used '62 122 from '63 to '67