My engine has had a knock ever since i got it, and ive been hearing a loud buzzing sound coming from the maf sensor so about three weeks ago i replaced the maf with a used one, ran the same for about a day. then it started to bog down really bad, and the truck would shake really bad on the highway, it just lost all of its power, so i put the old maf back in. the problem still didnt go away, so after talking to numerous mechanics i was under the assumption that my engine had died ( lost a cylinder).

I already had a used engine ready to go in so i decided to replace the engine. after replacing the engine everything seemed fine until i went down the road and realized that it has a very similar problem as far as the no power issue goes almost like its stuttering, so i ran the codes and got p0304 (misfire cylinder 4) and p1132 which i believe is a running rich problem. the exhaust definitely smells like its running rich. could this be an o2 sensor problem that still exists, its def not the new eng (i had it running before it was removed from the old truck and it ran great) im assuming that it has to be something to do with the comp or maybe along those lines. any help or suggestions would be greatly appreciated

 

buzzing sounds like a short but replacing didnt work? hmmm
Clean the MAF?
Timing off? I know those 4.0's are notorious for that misfire crap.
You could check the O2 by borrowing a friends just to see.
If you got no code for 02 and its plugged in then its fine.
get it flashed at your local ford dealer

 

I have cleaned the maf, What's the best way to check the timing? And I'm assuming that getting it flashed also means scanned

 

No flashed as in 80$ (last time my security system messed up) and they plug in your dash and set all defaults for engine back to factory. so in essence clearing any faults and starting the ECU over