This one has me stumped:
New plugs and wires, spark is good on all cylinders. Compression is great 132 +/- 5 PSI on all four. Jeep has 140K miles. Plug wires rechecked and ohmed, spark checked when cranking and all looked good. Injectors 3 and 4 swapped and misfire stayed on cylinder 4. Injector wires swapped and misfire stayed on 4. When idling, unplugging injector #4-which makes no difference in choppy engine, but all other 3 cylinders will stall engine. Fuel rail removed shows similar good spray pattern on all four injectors. One can of seafoam ran through is desperate failed attempt.
No other problems except erratic oil pressure (will be checking will manual gauge this weekend). No soft (pending) codes, but will throw the P0304 within 5 minutes after clearing.
Only notable potential issue may be PO has a less than clean 02 sensor transplant, but no 02 codes are thrown and my current scanner is not reading 02 frames.
Throw me a bone. I promise to followup with fix