1998 E-150 Misfire P0306 on V6

Hi, I recently have been trying to help my buddy out with his Van, he has had the same misfire for over 2 months now. The only thing that stops his E150 from running like crap is pulling the TPS sensor..here are the results I got from the scan tool. Any help would be great.

He has already replaced the ECU, TPS, and did a Fuel injector service on the cyliner in question.

Year: 1998
Make: Ford
Model: E-150
Engine: V6

Stored:
P0306 Cylinder 6 Misfire Detected


MIL ON
Misfire Monitoring Complete
Fuel System Monitoring Complete
Comprehensive Component Monitoring Complete
Catalyst Monitoring Complete
Heated Catalyst Monitoring Not Supported
Evaporative System Monitoring Not Complete
Secondary Air System Monitoring Not Supported
A/C System Refrigerant Monitoring Not Supported
Oxygen Sensor Monitoring Not Complete
Oxygen Sensor Heater Monitoring Not Complete
EGR System Monitor Complete

DTC for which Freeze Frame was Stored P0306
Fuel System 1 Status Closed Loop
Fuel System 2 Status Not Supported
Calculated LOAD Value 79.22 %
Engine Coolant Temp 203.00 °F
Short Term Fuel Trim - Bank 1 -5.47 %
Long Term Fuel Trim - Bank 1 10.94 %
Short Term Fuel Trim - Bank 2 -10.16 %
Long Term Fuel Trim - Bank 2 -0.78 %
Engine RPM 1183 rpm
Vehicle Speed Sensor 42.25 mph
Distance since DTC Cleared 2.49 mi
Barometric Pressure 0.00 inHg
Bank 1 - Sensor 2 Equivalence Ratio 0.00
Bank 1 - Sensor 2 O2S Current -122.00 mA
Bank 1 - Sensor 4 Equivalence Ratio 0.00
Bank 1 - Sensor 4 O2S Current -128.00 mA
Bank 2 - Sensor 3 Equivalence Ratio 1.01
Bank 2 - Sensor 3 O2S Current -127.00 mA
Catalyst Temperature Bank 1 - Sensor 1 -15.52 °F
Catalyst Temperature Bank 1 - Sensor 2 -40.00 °F

When is the last time the plugs have been changed?Also stay away from Bosch plugs in a Ford.It could be plug wires also.

There was a full tune up done on the motor after all the problems started popping up, wires, plugs, etc....

He always uses high quality stuff....

I was wondering if the reading of (0) on the Barometric Pressure sensor means anything.

I would pull the plug for no.6 cyl and check if its firing correctly. Ohm the wire between dist and plug I've found new wires with a bad crimp. Use carb. cleaner and spray around the intake edges and any connecting hoses. If you find a leak the engine will smooth out when the spray hits it. spray around the injector as an air leak around the injector will cause a mis. the o-rings sometimes leak.Pull the temperature sensor and clean it scale will cause them to read high. The temperature appears high. I would check on the barametric pressure as its not correct. Make sure the air filter is clean. Pull the vacuum hose on the pressure regulator if it has gas in it replace it. Also check operating fuel pressure as to low or high pressure will cause them to run rough.
I would try these before starting to ohm wires.

What did you ever find a leaking valve or weak valve spring will cause problems? Check the compression on the engine.