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Automatic highway RPM question

1K views 3 replies 2 participants last post by  GrrrraaberU3 
#1 ·
I'm running a 87 octane bama tune and I can't remember if the car did this before or not. I just got back from a trip to florida and got 25mpg highway. I am a little bummed because last trip I got 28. The only difference between trips is switching from a 93 tune to 87 going from stock v6 wheels to 18 by 8 all around and i went 78 the whole way instead of 75. Anyways the rpms at 78 are 2250. Well if I go down the hill the car almost is engine braking on cruise control. The engine revs to 2500 all the way down the hill and then when you give it gas again it revs up and almost shifts back into gear. I took OD off and its not that its coming out of OD and going into 4th. Its engine braking almost. I took a video which I Will try to post. I just wanted to know if this is normal also if the MPG is normal. I average 19 with mostly city. Thanks
 
#2 ·
#4 ·
Okay well that makes sense. The only other thing is the RPMs. Also at Idle the RPMS will flutter if I turn the vents on, not even AC. Is this normal? I took a video if I have to post it. It makes some engine noise that is annoying.
 
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