Limp mode? Bad transmission? Bad cats?

[fknchino]

Lexus IS300 2001 2jzge

I think my cars on limp mode. Revs won't go pass 2.5k, stuck at 20/30kmph.

Cleaned the MAF, in fact I replaced it recently earlier this year.

Changed out all 4 o2 sensors over a month ago.

Just changed the diff fluid, transmission fluid and power steering. It was fine after that, although I suspected it wouldn't shift to third gear, but when I went to turn it on again the second time, still the same issue.

I also hear weird grinding noises from time to time from beneath the car when driving

NO Cel, and throwing no codes either

Update: I disconnected the battery last night and reconnected it this morning. I drove it around the block and it shifts to third and fourth gear without making any sounds, but not fifth. the engine has a roaring sound and won't rev past 2500.

Parked my car and it revs up to 4k

[ilv1004s]

transmission?
or TB