Already swapped plugs, coils, and injectors with other cylinders. also ran compression on all cylinders, resistance on both coils and all injectors, everything is consistent and within spec. #4 continues to drop a misfire CEL. any ideas? the misfire can be felt throughout the rpm range, including idle

 

Replace the coils.

Like you, I tested coil resistance, ohmed the wires, replaced the plugs, even pulled the fuel injectors and cleaned them with a home made rig. All checked good. I then broke down and replaced the coils and all was well.

Autozone had coils in stock for $44 each (at the time). I thought they would be el-cheapo chinese knock-offs but was pleasantly surprised when an OEM Volvo coil came out of the Duralast box.

 

Replace the coils.

I had the same problem and bought the AZ coils (OEM Volvo) and everything is fine now.

 

Replaced the plugs with autolite double platinums and the misfire disappeared!

 

had the same thing i changed coils and had to do the wires.wires were breaking down under a load.