As the title says, would an issue with the throttle position sensor cause an engine to go into limp mode?

 

If it is an AT, it will cause erratic or no shifting issues, which would limit drivability as the TCM would not know what the driver is attempting to do.
Most of the computing power in the ECU is used for calculating air mass. The simplicity of a Speed Density system is also its own downfall as it heavily relies on a limited amount of input(sensors) and has to extrapolate what the drivers demands are and what the engines needs are. When any of the sensors are out of spec it can cripple the vehicle.

 

thanks, yes it is an automatic and won’t rev past 3000 rpms, almost feels like it’s stuck there. Shifts fine at lower speeds though.

 

Best to back probe the TPS and watch the voltage change, it should be a smooth linear change in voltage from closed to WOT and back to closed.
If the voltage output is erratic, verify the wire harness is undamaged, the pins are not corroded/damaged, and the various grounds and bonds are intact.
If there was any recent work or incidents that happened to the car, check the areas of likely work/damage.
Other test is to find an empty stretch of road, preferably an on-ramp and punch it. Floor the pedal.
If the engine revs and upshifts at WOT shifts then it is most likely a failed TPS/wiring/harness issue,