Nitsuj8952

I have a 2003 f150 4x4 with a 4.6 auto with 156k on the odometer. I got the truck a couple weeks ago and prior to me owning it, it sat for about 2 years. It started out with a miss so, I changed out all the spark plugs and put fresh 93 octane in it with Lucas injector cleaner and also ran seafoam. Seemed to help a little bit but still missing. Drove the truck about 10 miles and it started running on 7 cylinders. I drove it until it threw a code for misfire in cylinder 2. Changed the coil pack and it ran fine. Next day I drove it to work, started running on 7 cylinders again. Misfire in cylinder 1. Changed that coil and it ran fine. Drove home from work yesterday and upon startup I could smell it was running rich and it ran rough at idle and died at a stoplight. It threw a couple codes for bank 1 and bank 2 running lean and for the o2 sensors. I checked for vacuum leaks with a propane tank and found nothing. Found out the egr tube was welded where it connects to the exhaust manifold. I can hear its leaking so I plan on trying to repair it temporarily tomorrow with exhaust putty and bandage. I was just curious if this could be my problem or if there is something else wrong, eg. Temp sensor, fuel pressure regulator etc... any help would be greatly appreciated. Thanks!