Loss of Power in 3rd Gear Only
 

Hey guys, didn't see this issue addressed in the forum already so posting here. Post the link if I missed the relevant thread, thanks!

Driving a 2002 Mazda Protege 5 Hatchback L4 2.0L and having an issue with the transmission. I noticed the car was being pretty sluggish and felt under powered (I've driven another protege, same model and year) so I've replaced spark plugs, cleaned the MAF and throttle body, and started looking at O2 sensors and the catalytic converter. Since replacing spark plugs and cleaning the MAF and throttle body, it's become a lot more peppy in 1st, 2nd, and 4th but there's any issue with 3rd. After shifting into 3rd, the car struggles to get to RPM's up even if I floor it.

Anybody seen this before? I'm a hobbyist, certainly not a mechanic by any means, and trying to keep the car in running order as long as I can.

Definitely sounds like a transmission issue, I would book it in with a transmission shop for assessment.