Runs rough

The next is to put things back together make sure your coils are secured clear codes.
First start engine and idling using a test light (remove injector cylinder one connector)check to see you a pulse light on test light while is idling.
Second if it is pulsing light it means you are okay there replace all spark plugs, and cylinder one ignition coil with a new one. Once you have done that erase codes again and scan again this time with ignition on engine off, if no codes show then proceed to start engine allow engine to idle and watching the tester to see if any other codes appear then p0300, listen is the engine misfiring, remember any small vacuum leak can cause a misfire indication.
Remember to replace the spark plugs.
This technical bulletin possible that it applies to your vehicle.
To run this procedure you will need a tester that you can check live misfires on the tester it will show the cylinders what there are doing while it is running (it will show all cylinders and have 0 and when that cylinder misfires the 0 will change. Then when it is misfiring it should change to for instance 100 + or -. Write witch cylinders show misfires.
See chart on Technical Service Bulletin.

Cheers, Nick

Yes were right if you can do cylinder leak or go to tear down not waist any more time read the tech bulletin and move forward.

Cheers, Nick

It is time to tear down start with valve covers you will be able see cam lobs and move your way down, if you had a bore scope you can see inside, valve and combustion area. The best way is rebuild short block ask around for prices.

You can insert a socket in front of the crankshaft and use a ratchet, or lift vehicle and go to the flywheel.

Pull the plugs out and use the drive belt to turn it over. Been able to do that on many 3.7s. If nut a strap wrench on the crank pulley with the belt off works. Or a faster way would be to use your compression tester. Pull the one way valve out of it and use it like a leak down tester. Rotate the engine so both lobes on 6 are up, apply some air pressure, air rushing out the exhaust or intake (they normally drop the exhaust seats) and you have the culprit. If it's a bad seat the rocker is going to be very loose as well on that valve.

Okay, if the lobes on the cam are up so the valves should be closed because the rocker arms are on the lowest part of the cam you shouldn't hear any air through the intake or exhaust, you might hear a little through the oil drains because no piston seals perfectly, but if you are hearing air out the intake the valves are bad and the heads need to come off. At that point it doesn't matter if it's intake or exhaust as they are leaking. Those engines tend to lose the valve seats or the lash adjusters will pump up hard and the rocker will push the valve down and just touch the piston as it returns and you get a leak.
If you opt to replace the heads rather than rebuild them, be careful as to which ones you get, they are different over the various years. You would need the ones from an 05 or 06 for them to work properly.

I would agree with that, including the ownership provision. I would price it out and see what the owner wants to do.