2003 Ford Taurus No. 5 cylinder does not fire on idle

My 2003 Ford Taurus LX has 47,000 miles, a 3.0 V - 6 cylinder OHV engine (engine code 2) and is not firing on cylinder No. 5 when idling. At speeds above idle, all cylinders appear to be firing OK, but the engine runs roughly when idling. I am getting normal mileage of 25 mpg on the Interstate at full speed.
The amber “Check Engine Soon" light is ON steadily, but if I am sitting at a red stop light for a minute or so, the “check engine light" starts blinking and the engine really gets much rougher. When that happens, when I accelerate to go at higher speeds with the amber light blinking on and off, the engine becomes so much rougher that I need to stop the car, shut the ignition off and re-start it to get rid of the blinking amber light and resume to the steady amber “check engine soon" light, when the only roughness in the engine is detectable only on idle, once again. The extreme roughness disappears after I follow this process.
Auto Zone did a free diagnosis for me, and 2 codes were detected;
1. PO316 Definition – Crank sensor condition
Explanation – the Crankshaft Position sensor signal is monitored for error
Probable causes - 1) Crank sensor defective
2) Check connector and wiring to sensor
3) Check trigger wheel for damage

2. The second code detected by Auto Zone was P0305
Definition - Cylinder misfire detected – Cylinder No. 5
Explanation – the power train control module monitors the crankshaft speed and has detected a misfire condition.
Probable causes – 1) ignition system fault – spark plug(s), ignition wires, coil
2) vacuum leak
3) injector fault
4) high or low fuel pressure

So far, I have switched the following parts from my other Ford Taurus, a 2006 model;
The camshaft position sensor, ignition wires, new spark plugs, ignition coil, new fuel injector for No. 5 cylinder.
I have checked as best I was able for a vacuum leak by spraying water on the hoses and looking for bubbles and installed a new fuel filter as a makeshift measure of alleviating some of the possibility of high or low fuel pressure. I also switched the mass airflow module with my 2006 model. None of the above has had an effect.
A compression test was done on all 6 cylinders. Number 5 cylinder measured in at the lower end of its acceptable range, but still acceptable. The other 5 cylinders came in at the upper end of their acceptable range.
I do have another problem with the car which might or might not be related to the above problem, and that is the fuel gauge indicator (mechanical) is intermittent. It shows either 0 fuel or actual.
I hope that you have run into this kind of problem before and will recognize it and will be able to advise me what to try next.