I went through all sorts of trials with my 14", and have experience trouble just as you are having. Mine is a 14", 1HP, with a riser block. I have upgraded the spring, have installed Carter bearing guides and such. I have used many different blades. I have cut extreamly hard woods 8"+(ebony, cocobolo, Zircote and such). It sounds like you know how to set your machine up spot on (one thing that can be tricky with small blades is making sure your fence is parallel to your blade, if it is off it will mess with you- I only mention it as a thought just so you can confirm it is true). I had suspected all sorts of issues, from guides being off, tension being too low, poor tires and so forth Thus leading to the long list of upgrades. I got to the point where I could get it to run very well, then I slowed way down on oily rosewoods and such. If there was a problem I chalked it up to a bad blade.
I finally got tired and picked up an 18" saw. It performs like a champ, but I learned a few things, mostely because I have absolute confidense in its ability to hold a tight tune. One time I was going to run a bunch of wood, and set the fence and went for it. After running maybe 30-40 cuts through I shut it down for a break. I happened to notice I had not pulled the tension lever. This clued me into something about tensioning the blade. Even if you have a blade tensioned way below its rated spec. it will cut fine. I am not saying not to tension a blade properly, but it pulled it way down my list of "suspect" issues. I was curious about guides and how important they were. So I ran a test. I pulled my guides way back, leaving only the rear guide in place, but set way back(I did this only to make sure I didn't push a blade off a wheel). I ran the cuts, and had no issues. Again I am not saying to forget your guides, but they are not needed if your blade is cutting correctly. I ran several hundred cuts one day, and finally got to some Cocobolo billets. The first cut went pretty ok, the second went wacky. I cleaned the blade which had gummed up notably. Then grabbed a Koa billet, and it cut smooth as silk (about 20 cuts). I grabbed the Cocobolo and bam first cut went so so, second poorly. The blade had gummed up again(although after cleaning the blade was sharp and good to go). This got me thinking about clogging, clearing, TPI, feed rate, and how much these things can directly and significantly effect your blades cut. I switched over to a blade with 1.2 TPI, slowed the feed rate a bit(just enough to know it was clearing well) and all the sudden I am back in the game. The blades I was using, first was a 1" 2/3 TPI trimaster, then switched to a 1" 1.2 TPI woodmaster.
The long(and that was a long explanation
) and short of it is that I have learned to focus on the blades ability to cut and clear well. Granted my 14" is still temperamental about holding its settings, but as long as I have kept the blade cutting well I have had little trouble(I still use it off and on for cuts). It still gives me fits with very oily wood, because I need a blade that clears better, but as long as I watch the feed and keep the blade clean it cuts ebony and harder woods just fine. Try looking close at how much dust is being trapped in the cut after you run the piece. If you see much dust wedged in there it is not clearing well enough, if you see any build up brush the blade with a wire brush and clean the sides of the blade with a razor. If you see scortched dust or carbon building on the blade, again it is probably not clearing and causing friction. Carbon blades will dull much faster than carbide tipped, but usually they last twice as long as most people probably figure (a lot of sharp blades are just dirty). Blade wander from side to side seems to usually indicate clogging to me. A wide sweeping cut usually means the blade is not aligned with the fence. A blade that is bowing usually indicates clogging or overly agressive feed, which would be compounded by a blade that was not tensioned well. A blade that walks to one side strongly can also be build up on one side of the blade or bearing guide, turning the blade.
Hope that helps,
Rich