2001 Other Dodge Models P0304 and P0300 OBD II Codes

Engine is in a B1500 Dodge full size van. Subject codes continuously pop and causes check engine light to come on. Engine runs rough at idle after coming to stop light. I assume this is where/when the code trips. Runs fine at high power. I've read all the fixes. I've changed plugs, wires, cap, rotor, IAC valve. I’ve checked all vacuum lines. I’ve removed the throttle body and cleaned and sealed the gasket. Coil was changed a few months ago due to corrosion (bad location). This coil appears good. Resistance checks are OK. I pulled the crank position sensor and looked at it and did not see any damage. Engine runs so I guess it is OK. I am assuming that the camshaft position sensor is built in to the distributor (where the points used to be)? So those are the only two electrical parts not changed (that I know of). I pulled all the fuel injectors and powered them open and cleaned them with carb cleaner and air pressure. They seem to flow OK. Compression check is curious. Cylinder 4 (and two other cylinders) appears to have worn rings. Compression dry is down around 70 psig and around 90 pisg wet. Vacuum gage is steady at about 15 or 16 inHg. I have verified that the cylinders are getting fuel and they are getting spark. However, if I remove the plug wire or if I remove the fuel injector lead, I get no appreciable change in idle performance. I've swapped number 6 and 4 injector leads and no change. Pulling strong cylinders (either electrically or fuel) results in engine running rougher. I have not changed the Cat. I did change an O2 sensor about a year ago to correct that code.

Questions (finally): Is it possible that the low compression is resulting in misfire codes. Cylinder is firing (with fuel) but obviously not performing. My basic question is that if this is what you think might be going on, how does the computer know? The cylinder is firing. I know it is. Timing light says so and fuel injector says its getting fuel. It might not be producing power but it is firing and getting fuel. So, how does the computer know there is a "misfire"? Also, if this is what you think might be going on, is there any fix? I can’t pass emissions. Vehicle runs fine with the exception of a little jumpy idle at a stop light. Seems like a big price to pay for a sticker. Do you have any other thoughts on this? I would appreciate any insight. What have I overlooked? Thanks!