I have a 1999 Dodge Ram thats not starting, do I need a new engine?

I got a '99 Ram automatic, w/ a 5.9l engine. My problem started a couple of months ago, where my engine light came on and threw a P0306. I checked the sparkplugs on cyl 6 and found a hairline fracture at the inside porcelain, and replaced all the plugs. Engine light went off. Few weeks after, my engine light came on again, pulled the code 0300, 0306, 0308 all misfire related. I also noticed, that at highway speed, my RPM's starting to jump up 150-200 rpm at times, in 2 sec. intervalls. So I went through the plugs, wires and distributer cap. Cap contacts looked a little oxidized, replaced it. Started fine ran like a champ and light went off. RPM problem persisted though. 3 days later after driving it every day, it started running very rough and wanted to die at idle. I had to keep my foot on the gas to keep it running, made it home, parked it. Went out the next morning, to start it. Started up fine, then after 2-3 min. started running rough again until it died for good. The weird thing is, NO engine light on.... So I did my research and found that all the symptoms pointed towards a bad crank sensor. Replaced it, (took me 4 hrs, due to the location) still a no start, no engine light. Every once in a while it sounds like it does, but it doesnt. I also checked for Spark( nice and blue), fuel ( getting plenty of it, almost seems like it floods, due to gas smell) and I hear a very good compression during cranking). Have not done a compression test yet, since i dont really know what I'm looking for. as in air leakage or normal PSI range. Motor has close to 200k (i know...)but has been very well taken care off. Dont think its a headgasket, since it never smoked at all and coolant looks normal and keeps at level. Please help, I'm out of ideas.