120,000 miles on it and whenever it downshifts it jerks into gear. I was thinking about changing the trans fluid but I don't know if that would just create more problems. Any suggestions?

Trans jerk is a sign of wear and tear. You don't say how many miles its done? Is the trans fluid level correct? When was it last serviced? Have you asked a good home mech/garage to ride with you to see fault?

You have a failed transmission that will have to be
rebuilt or replaced with Reman

The flair in the rpm & gear change issues, should
have been the clue

How does that happen on a 7 year old vehicle ?

You fail to change your transmission & power steering
fluids every three years & those items that should last
15 years & 150,000 or possibly more, are given a death
sentence.

Trans fluid breaks down from heat in about two years &
like all fluids the additive packages are used up

Brake Fluid --every 2 years
Spark Plugs --every 3 years or they wear & stress the
ignition system

Motor Oil-well-you do as you please

I change mine 3 times a year,which is about 4,000
miles
When we worked-four times a year

I have a 2014 vehicle that I got in march
Changed the oil this Monday at 711 miles
WHY- it has been in there 4 months (remember
3 times a year) BUT --i keep my vehicles 18 years

I have one that I have had 30 years

The trans fluid --I will be doing soon
WHY- because I once owned a trans shop
& know what wears & when

Most wear,you ask-yep-the first thousand miles
& this vehicle has NO Filter,just a screen

Change trans fluid & filter. If you have someone do the work, have them flush the system to get all old fluid out. Sounds like a valve body issue and a fluid & filter change should solve the issue.

Spark Plugs--change every 3 years, not over 70,000 miles
Bad EGR Valve
Ignition Misfires
Worn out O2 Sensors---- change front 2 at 100,000 miles
Clean MAF Sensor-----clean- once or twice a year

Your trans failed, because the fluid has to be
changed every 3 years,30,000 miles ,power
steering also 3 years

You could do a fluid change and change the filter. Sound like the valve body is getting a little loose and the fluid is getting passed the vales to quick and applying the clutches to fast and to hard.if you do a fluid change and it get worse put some STP engine treatment in the transmission and drive it. It is thick and it will tighten up the valve space even when it's hot.

When tranny was replaced, were all lines and trans cooler flushed? Was converter replaced? Try flush and refill trans fluid and replace filter.

Sounds like the band that controls 3rd and forth gear is almost worn out. Have you followed the recomended interval for transmission fluid changes? What does your trans fluid look like?

This is common problems to the transmission when the fluid is getting to dirty and the transmission fluid and filter needs to be replaced. The transmission fluid and filter should be replaced every 45,000 miles to ensure there is no dirt causing the shift servos from binding. The other thing to is that when the transmission fluid get's to dirty, the fluid gets thicker. It retains fluid retention which can cause conflicts in the transmission sensors. What your experiencing is, your transmission is not shifting back to first gear and sticking in to 2nd gear. When you get on the gas peddle, the transmission sensors realize that it needs to be in 1st gear, so as the engine's RPM goes up and the transmission drops back to 1st, you get the jerking condition which will in turn cause you a $2,300.00 transmission replacement. For now when starting off from a stop, let the engine creep forward on it's own first to ensure that the transmission has shifted in to 1st gear. Then get on the gas peddle lightly till you have the transmission serviced. $100.00 transmission service is better then $2,300.00 transmission replacement. Good luck and do not have a transmission fluid flush, just filter and fluid replacement.

Check the universal joints in the drive shaft to rear axel. 120,000 miles, its time for replacement. Safety hazard exist, check soon. Also transmission filter should have been serviced at 60,000 miles. Its time.

Manual trans as well as auto trans,the fluid should be changed once a year and/or every 30k miles.