A REAL puzzler

I have a 1994 Camry with 170K miles on it (so it’s still almost new) and a couple of days ago it wouldn’t start. It cranked, started to turn over and stalled. Then, when I’d try to start it, it didn’t sound or feel right. It sounded like everything wasn’t turning when the started turned. Also, it seemed to crank too easily like there was no compression. I thought the timing belt broke or jumped (Improbable since the belt was changed at 120K)so I took off the cover, checked it, everything looks fine. Later when I tried to start it, it sounded right, like there’s compression and everything’s moving but it wouldn’t start. I checked for spark, gas and compression, I seem to have all three although that can’t be or the car would run. Also, the day it wouldn’t start it was 20 degrees and the day before that I had the rear of the car jacked up (properly by the jack point) to change a tire. I am a stumped chump. What did I miss?

How many psi on compression test for each cylinder?

And BTW, when’s the last time the oil was changed and what grade is in it now?