I have a 94 dodge spirit with 53,000 miles. Had a tune up done this year and just had a timing belt put on last week. When driving after 10 minutes it jerks. Around 45m/h I have to put more pressure on the gas for it to go back to speed. When driving on highways it goes the speed limit but will jerk. I've taken it to pep boys and was told the engine is fine and it could be a transmission problem. I've had a couple of friends drive it and was told that it probably needs transmission fluid change with a new filter. It could also have a gear problem.
Any advice will be helpful.

Yeah, and I'd also check the fluid level, when the level gets low, they tend to want to go into gear hard, or are jerky, old dirty fluid, and a clogged trans fluid filter can also cause it to be jerky. Trans fluid change/filter is a cheap thing to try.

Thank you for your respond to what could be the problem. I've found the reason for the jerking. I had not too long ago replaced the grear piece and I was driving in the wrong gear.
Thank you for your respond.