I just bought a used03 tl..one owner...i had the checked by a mechanic to make sure the tranny was good...he gave me the ok...so I bought it..been driving the car for almost a month..replaced the brakes and rotors...and did a tune up...recently my car started buggin out and hitting 5000 rpm and jumping down to 1000 rpms in a few seconds...casing the car to jerk...very scary...idk if it can be something nb esides the tranny itself...maybe a sensor or valve...does this sound familiar?????..please help!!!!

 

welcome to the forum
walk us thru this a little ok: you are cruising on level road at what speed, and the rpm suddenly goes to 5000? then drops and goes back up?

or are you on the gas hard and it acts up?
or what situation?

 

in the`tune up` what spark plugs were installed?
If anything except the NGK $8 each plugs,,example 2$ ac delcos-or bosch multi pronged,,,-thats your major problem
the TL ignition fries ordinary plugs in a hurry

whats the cars mileage?
running 91 octane gas?
did it start right after the tune up? what was replaced then?

 

any CEL light on the dash--flashing or solid?

 

trannny broke you went too fast too hard too many times? in the last month?

 

My Mothers Pilot does something similar to what it sounds like yours is doing i think..from what you said whenever i drive it quickly it will jump up to about 5.5 6k and then ill slow down easily...but its almost like it wants to slow down faster so it will down shift from like 3k to 5k and it will jerk like a b**** and slow me up way faster than intended. I just assume its not used to being floored like ever.