This is a great question, but we must examine what "acting funny" means when referring to one's drivetrain before recommending a course of action. Do any of the following seem familiar to you?
Slipping
When an automatic transmission seems to slip in and out of gear, or the engine revs up but the vehicle goes much slower than the engine seems to be running, it's known as slipping. Sometimes the gears reengage harshly.
Shuddering
This is where the whole vehicle shudders and shakes while driving, as if it's having a convulsion. It feels like you're driving over rumble strips even if you're on a smooth highway.
Neutral Drop-Out
A condition that feels similar to slipping, neutral drop-out is where the transmission drops into Neutral when the vehicle comes to a stop or while driving, typically at slower speeds. Sometimes when driving, the trans drops out of gear resulting in the engine racing up, and then either sliding — or banging — back into gear, or you step on the gas and the engine revs but the vehicle goes nowhere as if it's in Neutral.
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