Low Power / Surging during moderate acceleration

I have a 2005 Tacoma DBL cab 4.0l automatic. I have noticed for some time now that when the engine is cold is has a slight stumble when started for the first time. Until recently that has been the only thing I have noticed. The other day I went to take off from a stop sign and it was like the gas pedal was slow to respond the my acceleration demand. I thought it was just in my head and continued on with my day. I then was on the highway and wanted to accelerate and I could feel a slight surge when under a load in 4th gear. The Intake sounds as if I'm really pushing on the gas but engine rpms slowly increase, Torque converter was locked and rpm's were not fluctuating. It feels slightly under power as if I had weight behind it. Not sure if this could be a problem with the pedal position sensor or what? Truck has 93k. Any help would be greatly appreciated!