After the tune and intake my car started surging a bit at about 1500 rpm's. Decided to do a little exploratory surgery on the Stang, cleaned the throttle body and it helped but it still did it slightly, it seems to have stopped now.



The intake valves were dirty as hell

 

What brand of fuel are you using and how often are you using a fuel system cleaner?

 

I bought it used bone stock a few months back with 96k, I use Shell or Chevron.