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. (08/2008-Current)
M3 Coupe, Steel Gray Metallic on black leather, HK, three pedals.(01/2015-Current)
Last edited by X3-terrestrial; 11-25-2012 at 08:55 AM.