Hesitation under load and no CEL, could be a sign of gas starvation. It could be just a clogged fuel filter or a fuel pump going bad. But in order to diagnose a fuel pump, you need special equipment to measure fuel pressures.
Also O2 sensors have been known to produce hesitation under acceleration when they start to fail, although not triggering a CEL.
"If everything seems under control, you're just not going fast enough"
River City Bimmers BMW CCA
2005 X3 3.0i
ZPP, Htd seats, Htd strng, Black Sapphire on Terracotta.
M3 Coupe, Steel Gray Metallic on black leather, HK, three pedals.
1991 E30 325ic, AW, Black Leather, Black top, Three Pedals.
Last edited by X3-terrestrial; 11-25-2012 at 08:55 AM.