jkendal,
The main differences are:
1. My last 2 beers I've been less diligent about getting it into a keg and I've had them sit in secondary longer. Normally I'd ferment 2 weeks, 1 week in secondary and then right into the keg.
2. Used Pilsen Malt Extract, which I'd never used before
3. Been having keg issues and had 2 kegs go bad so I'm paranoid and not using that particular keg anymore.
4. Wondering if I need Food Grade CO2 or to clean my CO2 hoses?
You can see I'm all over the board here, but I've done 18 extract brews this calendar year and the last 2 have been cloudy when the rest have been crystal clear. You can see why I'd be puzzled and wondering if it's equipment related.
OK, you're not bottling, correct? Normally I associate chill haze with bottling. If you're kegging only (like me) and you haven't experienced this before using pilsen LME (which I've never used), you might need to let the keg chill a bit longer. I usually crash-cool my fermenters a few days before kegging (sometimes a week). Then I let the keg sit a week on gas at serving temp while they carbonate naturally. And I wouldn't worry about leaving your beer in secondary for longer than you normally do. Longer is most often times better anyway.
As to the problem with your 2 kegs going bad, when was the last time you replaced your transfer tubing? I had an infection one time and couldn't figure it out. I was doing everything right to avoid infection. Then I read an article about spring cleaning and it said you should replace inexpensive items (like transfer hoses, stoppers, etc.) every year or so. I tried that and my infections stopped. Now I replace them every year. Tubing is cheap - a batch of brew isn't.
Also, are you cleaning your keg parts periodically? Just soaking in cleaner and sanitizer between every brew isn't enough. Try boiling all the keg's parts every 3 or 4 brews - especially the dip tube. Get a long brush for the dip tube, too - sometimes bacteria can hide in there. Replace all the rubber gaskets periodically (every year or 3).
EDIT: cleaning your CO2 hoses isn't a bad idea, either. Especially if you force carb and beer backflows into the tubing. If that's happening to you, I'd replace the tubing right away and stop force carbing. Let your kegs sit on gas at serving pressure (and serving temp) for a week, letting them carb up naturally.
And on the question of food grade CO2, that's only a concern if you're getting your CO2 from someplace other than your LHBS, like a welding supply company - if that's the case, just tell them what you're using it for - sometimes CO2 gas can have impurities in it that's only used in welding applications. At least that's what I've heard...