Lost power - low torque
 

I think I put this thread on the wrong spot yesterday, so posting here today.

I have a 2006 Mazda 3, manual 5 spd, with 2.3L engine. Has about 45,000 miles on it.

Recently, I lost a lot of torque. Just happened overnight. Now, the engine drives too "smooth", like grandma's car. Can't even burn rubber in first gear on dry road, no matter how hard I try. No torque.

Clutch shifts smooth in all gears. Clutch pedal is getting soft and quite close to floor, but no hesitation, chattering, or slipping. I have in past experienced soft clutch on another vehicle when there was air in hydraulic system, but does not feel quite same here.

This is my 4th vehicle with manual transmission. Others were old Firebird, Mazda B4000, and Ford F150. No issues ever with clutch on any of those. Ford clutch lasted me 110,000 Miles before replacement, and that truck was 4x4 off road and took a beating.

M3 has no real power in any gear now. Feels like it has lost 20% of power/torque. So have to rev it much higher than usual to get any power/acceleration. I know this is typically a worn clutch, but given that it happened overnight, could it be something else?

Could it be torque converter clutch, vacuum leak, something else?

I figure you would mention if the check engine light was on. Could be a plugged cat / dent in the exhaust or something. Possibly a mouse nest in the intake :)