Hangwire

Nobody is saying for certain you dont have internal engine issues.

It certainly doesnt make sense to crack the whole damn motor apart just to find that nothing is wrong. Start with the small things. You can take it from people who know these motors far better than you or you can assume(You know what assuming does).

REPLACE all ignition coils and spark plugs and go from there.

I spent a few weeks trying to trace what I insisted was a "knock" just to find out I was an idiot when I first bought my car. The valve-train/fuel injectors on these motors are quite noisy. When I am at part throttle/mild acceleration in overdrive I can hear my fuel injectors clicking away louder than my catless exhaust.

VTX1800N1

I understand what you are saying, however I'm also very familiar with all the noises Ford Modular motors make. I own a 2005 F150 5.4 3V with the infamous phaser diesel sound, and I've driven a Crown Vic at work for many years.

Moving the coils around and getting the same engine codes eliminates them as the problem source. Certainly we will ditch the Accel junk for Motorcraft or Visteon eventually.

I'll swap the plugs next. Their color will tell me a lot about how the engine is running. I don't expect the misfire codes will follow the plugs when I swap them around, but I'll give it a shot.

Further, I don't have to tear the entire engine down to locate what I suspect is the problem: collapsed lash adjusters. My plan is to run a cold and hot oil pressure reading and then a compression test on all 8 cylinders. That will tell me what I need to know about the internals. Then, assuming the plug swap doesn't reveal anything, I'll pull the valve covers. It's easy on the Mustang and I'll be able to instantly tell if the lifters are collapsed.

I'm not sure what gave you the impression that I don't know much about motors. I've rebuilt several over the years. I do all my own mechanical work unless I don't have an expensive tool (alignment machine, etc). Have been doing this for decades, and now I'm teaching my son on his first car. He's pretty excited about it and willing to learn. He has a mechanical understanding like me. He just got home from Army Basic and AIT: 15T, Blackhawk Mechanic. I've already taught him how to listen for bad lifters by comparing his Mustang with my F150 with a mechanic's stethoscope.

JC316

If you know these motors, then you should know that the lash adjusters won't cause a dead cylinder. It will knock like all hell, but it won't be the source of your misfire. Compression check is the right move. At this point, my money is on a burnt valve, or if you're lucky, a busted valve spring.

Hangwire

Did the guy you bought it from give any background on the motor? How did it end up the way it is?

A compression test will give you a good idea of the health of the rotating assembly/P. rings.

VTX1800N1

No. Mom owned it and her 18 yr old daughter drive it. She could no longer afford insurance with the daughter going to college. Neither knew anything about cars. I explained to her what I thought was wrong with it and what it would cost for a shop to fix it, giving possibilities from lash adjusters and rockers to a full engine replacement. She was firm on the $4700 asking price when we got there and we left with the car on a trailer for $2400. I'd post a picture but I don't think I have enough history here to do that yet.

VTX1800N1

Home on the trailer the other day...

VTX1800N1

Got a chance to take a peek under the motor today. The oil pressure sending unit is right out front, very easy to get to. I was afraid it was going to be a PITA like my F-150. Unfortunately I've been hammered at work and likely won't get a chance to do anything to the car until Monday.