Long drive-harsh downshift 2 gear to 1

[Tracied3]

I am the original owner of my 97 sonata, GLS, 6 cyl, currently at 130k.
I drive 150 total miles daily starting Nov 2001. I was at 45 k miles then when I started experiencing bucking in the 2nd to 1st gear. I took it to Hub Hyundai in Houston in November, changed my feul filter, air filter and cleaned fuel inject system. problem still exists. Had the transmission reviewed by specialist that said a transmission fluid change should help. Did mildly, problems still exist.
Get this, it only occurs only after I have driven at highway speed for more than an hour (or if really cold) but the dealership who has looked that this car some 10 times in the last year. The dealership says they can not get the car to duplicate it for them and they will not drive to College Station to see if it will occur for them, so they make more corrections that say should help. It usually does some, then I am back to the same problems!
On a long drive, coming to a stop, the car bucks forward and at certain times, the jerk was so bad I felt that surely the transmission would fall to the ground under the hood!
They have done the following:
replace fuel filter, replace a valve (or air intake valve) solenoid, thermostat, feul injection cleanings, replace engine mounts.....I have kept up all oil changes and fluid changes. Although I am at 50k miles on my transmission fluid at this time, which does smell burned and I am sure changing this will help some, but I am sure the problem will still occur.
No one seems to have any advice. Honda 98 civics have a lot of documentation about these problems and they have replaced the transmission which after 30k miles, the symptoms start again on those cars as well. The dealership acts like my car is the only car to experience this and I know that can not be! The Transmission specialist pulled up all data and said there are many complaints on the transmission (Mitsubishi).So I called the 800 Hyundai # that tells me my car is out of warranty. I freakin know this. They claim they never heard of my transmission horrors and advise to go to the dealer that says nothing is wrong! I have 2 payments left and can not afford a new car payment but this has been going on for over two years. i am not experiencing any other problems as far as driveability issues. I am unsure of my rights or what I can do. Anyone else heard of this or experienced this?

[GTPSPEED]

ok,first try the plugs cuz if one is misfireing it would surely cause this,if not it also kinda sounds like your missing a link in one of the gears so you should have that checked by a shop that speacializes in trannys,they will hook it up to the machine and go through all the gears and if it your tranny they are sure to find it,try that,i hope i helped a little,good luck man