pls help , my Yaris has problem !

[msh_hi]

hi everyone here

i have Yaris 2013 automatic

my problem is the RPM when it cold it is up to 1500 and it is go down until 750 almost , when i drive it the rpm start goes down like if i stopped at the traffic light it goes to 500 RPM and down down until the engine stopped !!!

sometimes the RPM goes down 500 and for seconds feel it will stopped but it goes up dirctly to 1100 RPM and go down again !!

i can see that the fuel usage is more than normal also

i text the computer . there is a sensor called speed sensor it it some time show up in the test and sometime nope .


i will be crazy pls help