Fuel Injectors....

[StockAlero00]

When is a good time to replace the fuel injectors, or to get them professionally cleaned? Does anyone know any signs?

Also I have some problem going on with my alero. I'll try my best to explain it, but it's difficult without either showing you, or being in the car. Well here goes,
Last week, driving around, I noticed that when the car is stopped at a light, it kind of jerks forward and back. It feels like it's coming from underneath me. It's not a side to side motion. At that time, I'm thinking it has to do something with the fuel line, fuel pump, or the injectors. Just a guessitimate.


So I head out to Pep boys, and pick up a bottle of fuel injector cleaner. Add to my car, drive to work and still does the same thing. This time just the service engine light would blink for 10 seconds then stop and did it once more. After work on my way home, no weird feeling from the car, no light came on. She ran great. Thought ok, it's probably my fuel injectors.

the next day on the way to work the same back and forward motion. No warning lights came on. So i am thinking that my injectors do need to be cleaned or replaced. That the bottle stuff just isn't going to cut it , or be enough.

I also noticed when driving her on the roads, or highway, after being at a set speed for awhile, like say driving at a smooth speed of 45 m.p.h, and I want to then give her more speed to get up to like 75 when getting on the expressway, I have to give her more gas. I sure hope it's not the tranny. Those things are expensive to fix.