You still have the same situation except you're dealing with 4 degrees extra instead of the 7 degrees extra. A lot of guys without tuners bump their base timing to 14, however, and don't have any problems. The stock Ford programming for the most part is pretty conservative. It's just something you need to be aware of if you don't have a tuner, that changing your base timing affects timing everywhere and that sometimes that can be bad. You should be fine at 14...you may be fine at 17 but that's pushing it.

The Fox computers control the idle rshared_pm by varying the timing so it may have a bit of affect. On my data logs, I see mine jump between 10 and 26 degrees at idle. I can't seem to get that worked out of it but the current tune seems to keep that under control better...time will tell. I would say your problem is probably a vac leak or exhaust leak that is messing with you. Exhaust leaks can pulse fresh air into the exhaust and your 02 sensors think you are running lean so they command more fuel to compensate. That causes you to run rich so the computer compensates the othe way and ends up chasing its tail. The result is suring and stumbling. Another thing you might do is to remove the electronics from your MAF and gently clean the little coils with an electronic cleaner that doesn't leave a residue. Sometimes you get a little oil on those coils, especially if you're using a K&N type filter that uses an oil on the element. You can suck up a little of the excess oil, especially i you clean and re-oil the filter and get a little too much on it. That oil can screw with the readings and result in some wacko problems. Couldn't hurt to clean it...just be gentle with those little filament coils.