Need Help with Miss problem

Hello, I have an 03 Lincoln LS V8 136000 miles. Just bought it in mid June and it was throwing P0420 and 430. I changed out the Coils and plugs and that seemed to do the trick. Before I was getting about 18.5 mpg and after it went up to 22 mpg. Well this lasted for about 250 miles (about a week). Now I have developed a really bad miss on #7,and a sometime flashing CEL, changed out the coil, no change. My question could this be a fuel problem? I did have one thing strange thing happen before I did the coils and plugs. I was just pulling on to the on ramp stepped on the pedal and it was like some one turned the car off nothing let off the gas and it was still idling tried again nothing, pulled off to the side. turned it off and restarted and it was fine??? Plus the fact it seems now that I my have to do the solenoid in the tranny grabbing during shifts.
So much going on and I don't know where to start.
Thx to all you readers,
Jack

Pull the #7 plug and make sure the gap is correct. You may want to replace it anyway.
Where did you get the coils from. Some of the non-oem fail right away. You could change the #7 coil and the #5 and see if the misfire moves to #5. Make sure the #7 coil connector is good and is latched in. Make sure the #7 fuel injector connector is good and it is latched in.

Don't worry about the ETC failure. It's often caused by EMI from a bad coil (#7 in this case).

Thanks Joegr, I,ve decided to get a OBD II reader. It should make my life a little easier instead of running back and forth having someone pull the codes for me. Plus be more productive. You are probably right about the coils they were cheap. Got the whole set for $70, but they are guaranteed for life they claim. I'm calling them this morning to see what we can work out. Just need to get this miss fixed so I can check and see how the trans is going to do.

Well the miss is gone. And indeed it was cylinder #7. My problem was I thought that one started on the drivers side, but actually it stars on the passenger side. When straight to it changed out the coil and all is well. Adding freon is a pain though. The low side valve is behind the front drivers side, why couldn't they just put it on top? Time will tell about the trans.
Thanks to ALL
Jack

... The low side valve is behind the front drivers side, why couldn't they just put it on top? Time will tell about the trans.
Thanks to ALL
Jack

Because the suction line does not come to the top of the hood compartment (unlike the pressure line). They put in the most practical place they could without increasing the cost to make the car.