1997 Lexus GS 300 acelerator problem

dear sir

there is no option for toyota aristo, thats why i put lexux gs300 because its a bit similiar

im having a problem

the car is discontrolled

first when it was normal, when i started the engine, the car automatticaaly acelerate a bit to warm up the engine

now i dont know what happeened, the car is making the inverse

its acelreating that bit when the engine is already hot, and when is cold the acelerator is norma;

please help me