(Only when decelerating) I experience a bump or shudder or jolt precisely when the car reaches 29MPH . Always and only when decelerating.Acceleration is as smooth as can be Recent observations. are as follows. No error codes on basic code reader. Transmission fluid was low...but now topped off. Transmission fluid dipstick "top" is not snug.

Shudder is usually a transmission concern with the torque converter. 40 MPH indicates a range in which the tcm engages torque converter lock up, and most shudder concerns happen at this time. Need a scan tool to be exact. Obviously could be another concern. Without driving I would not know. If it is a shudder, in my experience a complete transmission service with filter and friction modifier will usually remedy the concern in the short term... however... complete rebuild is not usually far off in the future. I have seen other internal transmission issues following this about 20 to 30,000 miles after fixing the shudder

first question =---manual or automatic
next are there any other symptoms ( slipping, shudder on take off, difficult to select 1st gear or reverse )
I would be looking at the drive shaft "U" joints and cv joints first because once a clutch is engaged there will be no noise under acceleration of deceleration
look for failed engine/transmission mounts and suspension rubbers worn out

Could be fuel pressure or a blocked fuel filter. need more test information,

wheel tracking is out. Take it to a tyre dealer who will sort it

You are describing torque converter clutch shudder.

acceleration is slow after 45mph
if I floor it, its doesnt have alot of pickup.
if I start out slow its fine,

Several things to check are wheel bearings and brake rotors. The rotors can have weights welded to them. Sometimes they rust off. Some manufactuers recommend spin balancing on the car.

When you spin balance on the car, you will balance the rotors at the same time. Two things to remember, mount the wheels exactly to the same stud if you take off the wheels for any reason and if you rotate the tires you will have to respin the wheels.

uneven air pressure will cause dips in tires.bad struts will also cause this.

I'd check the motor mounts. Shuddering upon acceleration indicates movement of the engine inside the compartment. Best of luck.
Greg

Engine smoke problem-- Automatic, chk transmodulator. If oil in vacuum line, modulator is defective. Engine sucking up trans fluid. 10.00 fix . good indicator is smoking at cruising speed or deceleration.
Bad rings smoke under acceleration and bad valve guides smoke on deceleration. poor crankcase ventilation (pcv valve) will cause engine leaks and oil blowing out of dipstick. Good Luck