2001 f150 v8 #7cyl. misfire, WTF!

Sorry Kylar if one cylinder is down to 30 psi you either have to look inside the engine to locate the problem, or get a replacement engine.

Jacko

coil

check plug gap .try a little hotter fire plug. sometimes the seals around the valve cover will let oil in around the spark plug causing it to misfire. as the 4 cyl engine has a coil pack and you cant see it till you remove it.

An auto parts store does not give out advise

They are parts counter sales people-- not mechanics

Spark plugs seldom fail in your lifetime, so you need to
check for vacuum leaks at O2 Sensors,Exhaust leaks,Vacuum leaks
in inlet ducting ,pcv vacuum leaks,egr system issues

Check & listen to hear if injector all click & have same resistance

An OBD Codes for a cylinder doesn't have to be correct

You have mechanical integrity also

You don't have the tools to test as needed I don't suspect
or you could check cyl contribution,fuel trim,fuel press,cyl misfire
counts,O2 switching times,etc

mcdevito75 here, Could be a worn timeing belt, a crankshaft position sensor. Have your local shop check it out.

Try the cheapest Fixes first 1) change the air filter. 2) change the fuel filter. Add 1 can of B&G44K to a full tank of 91 octane fuel. This additive is the best on the market and only available through dealerships(Do not substitute). It will condition the fuel pump and injectors. Try this first, Then redo the ODBII test. Erase all stored faults after reading. Put a dab of RTV on the bare wires at the crank sensor to insulate wires.

you most likely have a problem with you cylinder head. Very costly job, but it needs to be replaced. You can find a machine shop who will realign the heads and

You've tried everything but getting the timing checked out. You've done all the other parts of a tune-up but that.

When you changed the spark plugs did you notice #7 was especially dirty or greasy, this could point to a seal being broken or a piston ring that needs replacing.

Next change swap the injector with another and see of the problem moves.  If it does it's a bad injector.  

First things first: have someone use a scan tool to check for diagnostic trouble codes (DTC's). If the engine is misfiring, regardless of why(spark plug/fuel injector/ bad camshaft lobe, etc.), a misfire code will be set. These particular codes will begin with PO300. An example is code P0301, indicating cyl# 1, P0302, cyl#2, etc.
Then the diagnostician will need to examine the data for short term and long term fuel trim, oxygen sensor readings, etc. to pinpoint the area needing attention.

The problem could be as simple as a bad spark plug, a bad ignition coil or some other "external" problem.
An engine compression test, a simple diagnostic procedure, will tell you if you have an internal problem, like a bad cam, or valves, or something else which can affect engine compression. I am not familiar with Hyundai having camshaft failure problems. I don't know how many miles you have on your Hyundai, if your under 100,000, I doubt you have internal trouble. You need to make friends with a good auto technician!