when in park position,during firing, the car will not go above 2 rpm why?

have not checked valves/cam timing yet. i was thinking it has some thing to do with the brain box of the engine. the codes i got during scan is CAM SHAFT SENSOR BANK A, though i got other things like throttle cable sensor and air flow meter, but when i re scan again, the last two disappeared and only the cam shaft sensor bank a remained. i changed the sensor, although old ones, but at first firing, it raised to about 5 rpm but on second firing it could not go above 2 rpm

How many miles on engine?

Hello Sir,The miles on the car is 166060. thanks for your assistance.

My best suggestion, with the supplied information, is to either start verifying what you can physically-like timing chain/cam/valve condion and position, or get a scan tool that reads live data and learn how to interpret the readings/values on that, to assist in proper diagnosis, rather than continuing to guess. With the correct info and diagnostic tools, it may end up being relatively simple to diagnose(the actual repair still might be a pain).

I have not checked valves/cam timing yet. i was thinking it has some thing to do with the brain box of the engine. the codes i got during scan is CAM SHAFT SENSOR BANK A, though i got other things like throttle cable sensor and air flow meter, but when i re scan again, the last two disappeared and only the cam shaft sensor bank a remained. i changed the sensor, although old ones, but at first firing, it raised to about 5 rpm but on second firing it could not go above 2 rpm.