89rsragtop

I have a 2002 LS1/m6 in a 89 RS. The engine has a comp cam ported TB and exhaust. also a custom tune by Hawks. I was getting P0171 & p0174 and I couldn't figure out why. I now can draw the connection between that and down shifting too much mostly in heavy N.Y. traffic.(The old stop and go.). Has anyone had this problem? Is this a sign that I am overall running too lean and down shifting just puts it over the line? Other than that it runs great and very strong. I would like to hear some thoughts on the problem before I spend the time and money on a dyno tune.