If you're on stock injectors there isn't much reason to mess with the safc. Zero it out unless you have a logger in which case you can lean it out slightly accordingly.
Your problem sounds like nothing safc related unless you have it hooked up wrong or set on the incorrect type of air metering/cyl/etc.
With a 255 you don't need to worry about the injectors...it's the fpr which may be a problem. On 2gs stock fpr is 43.5psi I think and on 1gs it is lower (38 if I had to guess...look it up). I know most 2gs run fine on the stock fpr with a 255, 1gs usually do too, but the lower stock fp might make for more of an effect from the 255.
www.dsmtalk.com/forums is where you want to look for an answer...not here

 

i dont think any of this way cuased by the engine flush, i do it just about every day on cars at work. even though i have seen it give a few high mileage motors a rod knock. how many miles you got? dont here any noise do you? i just flushed my 4g64 and its fine