ONLY when i accelerate on the highway, speeds 65-75mph. The car rocks forward and backward like it's misfiring or something. the engine light is always on. I have changed spark plugs, wires, new battery and did a fuel system clean. What else could it be? Fuel filter? Catalytic converter?***2000 Chevy Malibu 160,000 miles V6 auto trans.
well it sounds like ya pound the crap out of it regularly, it might be one of three things, bad injector, bad TPS sensor or a ignition control module going bad. as to juniors comment, yes it can have a code to lead you to the problem, but remember one code can be caused by another item being faulty and it won't show it's self till the first item is changed.
If the engine light is on,there is a code stored in the car's computer. There is a sensor telling the computer that there is a problem. A cheap way to find out what the code is, Just go to an auto parts store like Autozone or Oreilly's and have them read the code with a code scanner. This will tell you what sensor is causing the light to come on and will help you diagnose the problem. There are WAY too many electrical parts on a modern car to just start guessing and changing random parts. It will nickel and dime you broke like that. The car will tell you what is wrong by reading trouble codes.
try the O2 sensors. most of the time the codes will read a misfire and you will end up replacing everything and still have problems. O2 sensors hardly come up in a code even if it is the problem. it could be a fuel filter but not likely. the cat wont go completely for probably 5 years so rule that out. good luck
