2000 Grand Am GT 3400 sluggish/low power
Hello. I have a 2000 Grand Am GT with a v6 3400. For over a year now I've been trying to sort out low power/acceleration issues to no avail. When i take off from a stop It feels like the car is being weighed down and It doesn't pick up speed as It should. Generally upon acceleration, i hit 3000+ RPM before the trans shifts into the next gear and i actually begin to pull away from the stop. While cruising, if i accelerate, the car always shifts gear before i actually pick up any more speed, even when I'm cruising at 55mph and accelerate to say 60-65. When accelerating, there is usually a pause between shifts almost as if It went neutral for a couple of seconds. When this is happening it literally feels like you've taken your foot completely off of the gas. Shifting is typically delayed and sloppy, often times not locking into 4th gear, but rather going between 3rd and 4th before locking in. Trying to accelerate after this also results in another upshift like i mentioned earlier. The car also always runs hotter than It should. I live in Michigan and over the winter the engine runs about 200-210 (my wife's. 99GAGT is about 185-190).
I've replaced the air filter, gas cap, thermostat, pcv valve and boot, TPS, fuel filter, catalytic converter. I've cleaned the MAF, IAC valve, throttle body/butterfly, and IAT. I've also swapped the MAF and IAC from my wife's 99GAGT. After nearly everything I've done the car has run noticeably better, but only for a few days to maybe a couple of weeks. I have NO SES codes other than a couple of EVAP codes.
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