问：我的力量损失，我真的不能太硬，否则发动机会开始摇动/停滞

When I start the car the engine idles at various rpms and will almost stall but never does and I usually wait it out for it to settle but sometimes I gas it to about 3.5k rpm and it stops changing and stays pretty consistent, any idea what it might be? When the car is rolling and I slip it into nuetral it goes to whatever rpm you want it to

My car has 160000 miles.
我的汽车有自动变速箱。