Best guess is you have multiple issues going on. Sounds like most of it is the CPS.
Not starting hot is a typical CPS issue-281 ohms sounds high. Make sure and inspect the CPS wires and make certain they aren't touching the exhaust manifold.
That plastic tube for the MAP can get tiny cracks or rub spots usually on the bottom, I can feel them with my finger tips better than I can see them. Be real careful of that plastic tube, it gets brittle with age. Also make sure the MAP vacuum line is plugged into the proper hole, there are two, one goes all the way through and one is a blind plug.
Check the O2, knock sensor harness where it runs behind the power steering pump. If it was improperly routed during a water pump change it can be cooking on the exhaust.
When/if you get spark again, pull the number two plug wire, use an old plug opened to .060, hold it on a good ground and look at the spark, a fat yellow spark or a very weak looking spark isn't good, should be white blue and have an audible crack sound when it sparks.
Double check the torque on your exhaust manifold bolts, being real careful of the end studs, they get weak from heat and tend to rust solid and/or just crack, break and fall off. I skip the end studs unless I'm sure of them and just tighten the middles.
If you have a valve cover leak at the rear and it has oil soaked the CPS, it can/will cause issues.