DTC P1121: Throttle Position (TP) Sensor Signal Lower Than Expected
WARNING: This page is about a different car, the 2004 Acura 3.5RL, 2003 Acura 3.5RL, 2002 Acura 3.5RL, and 2001 Acura 3.5RL. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition switch ON (II). Using scan tool, check throttle position. If throttle position is 14.4% or more when throttle is fully opened, problem is intermittent. System is okay at this time. If throttle position is not 14.4% or more when throttle is fully opened, replace TP sensor.