HELP! My Tracker has no get up & go...

Please, someone help me! My Tracker doesn't want to GO. I mean once it gets going it's ok, but trying to get it going is a problem. I just changed the fuel filter, thinking that would help, but it didn't. I've been told it could be the catalytic converter... or the oxygen sensor... HELP!!! Has anyone had a similar problem or know anything it could be... I'm a single mom on a limited budget and don't have alot of $$ to put out fixin this & that, trying to figure out what's wrong!!!!
thank you!

You might try advancing your timing to see if it runs better, if so, you probably have a worn slot in the timing pulley on the crankshaft, as well as a worn key and maybe wear in the crank slot. Happens quite often. Mark the distributor before you loosen and advance it so you can put it back where is was if need be. Ed

Do you have a manual or automatic transmission?

If a manual the clutch could be slipping, especially if the engine revs up but the car doesn't move quickly. A new clutch or adjustment will fix that problem.

If an automatic it may be low on fluid allowing the torque converter to slip and not transfer all the engine energy to the drive train. Check the fluid level with the car parked on a level surface, emergency brake on, transmission in neutral and warmed up, with the engine running. If necessary add the specified type of automatic transmission fluid.

Make sure all filters are new and clean. Make sure your gasoline is fresh and clean as well. A new fuel filter can clog up again right away if something caused the fuel to become contaminated.

Good luck.