My car is actin up. I have a 98 civic!!! I jus recentley did a motor flush, n a block seal. However, my car will act like theres no power going 2 it, until I floor it. N also, when I come up 2 a light or stop sign, it'll shut off!!!!! The idle also goes up n down as well. When im @ a light, I have 2 keep my foot on the petal, n give it gas. What can it be!!!! 1 of the sensors

 

Could be a TPS or O2 sensor.