Topic: Uncommanded acceleration; lack of acceleration; incidents occurred over the course of 3 weeks (used 2006 Acura MDX purchased on April 12, 2010). Shortly after purchase, vehicle exhibited "stumble" when accelerator was pushed. That is, the engine RPM decreased with increasing pedal pressure. Pressing down aggressively resulted in engine idle condition. This occurred 0.5 miles from home. Problem did not continue the next morning. On May 3, 2010, while coasting through an intersection at approximately 35mph, vehicle suddenly accelerated without pedal input. Cruise control light was observed on (cruise control had not been engaged prior to incident). Light brake pressure stopped acceleration and vehicle returned to normal operation. On May 6, 2010, vehicle "stumble" re-occurred. Pulling through an intersection while pressing on accelerator, vehicle RPM dropped. More accelerator pressure resulted in more RPM drop. Pulled to side of road and stopped. With vehicle in neutral or park, engine responds normally to accelerator. Putting vehicle in any forward gear, problem persists. I was able to slowly accelerate with very gentle accelerator pressure, but rate of acceleration was very slow and potentially dangerous due to heavy rush hour traffic. I was able to slowly drive the vehicle approximately 3 miles back to the used car dealer where the vehicle was bought. At end of trip, vehicle was unable to climb a modest incline and I had to stop. Turned off engine hoping that problem would clear. Waited several minutes and tried to re-start. Took several attempts before engine would "catch" and run normally. Was able to slowly climb the incline back to the car lot. Problem persisted at used car lot. Vehicle was towed the next morning to Acura dealership in chapel hill, nc. Problem cleared and dealer was unable to observe symptoms. Dealer claims that there are no anomalous computer codes. I believe vehicle is unsafe to drive.

- Durham, NC, USA