97 lumina no start condition

Hi all. Hope you can help. (edited for clarity)

Got a 1997 3.1....cranks but no start. Battery is new and engine has good cranking rpms. 15F degrees outside and car has always sat out and worked fine until now it won't start.

Thought I had a bad ignition module or coils since the spark seemed kinda weak. Coils checked within spec but I just went ahead and replaced the ignition module, coils, spark plugs and wires since there was a bit of corrosion on the connections. Spark looks much better and is firing good on all cylinders with a spark tester but still no start.

Checked the crank sensor...850 ohms and .4 -.5 vac when cranking so it seems within specs.

Checked fuel pressure at the rail @43psi and it holds.

Still no start.

I am getting fuel into the cylinders (plugs were wet with fuel) I cleared the cylinders, pulled the fuse for the injectors and shot starting fluid into the intake and she just sputtered a bit and an occasional backfire but won't start. Reinstalled the injector fuse and same thing....a couple sputters and a backfire. I can see the rocker arms moving via the valve cover oil hole so the cam is turning which means the timing chain isn't broken, but it could be slipped? I've got spark, fuel, and compression but the thing still won't start.

Any ideas?

Thanks folks!

Ok, I did a compression test.

2= 160
4= 165
6= 175
1= 175
3= 105
5= 170

Did each one twice to be sure. Obviously the #3 has an issue but I don't know what is a "good" compression pressure for this engine anyway to determine if the timing has jumped. Also, the #3 could mean a valve or seal issue but I would think it would still start or at least try to. Any thoughts or suggestions you have are appreciated. Thanks!

Unplug the puter from the ign. mod. then try starting.