Yes, a clogged converter will rob you of power and speed.
A foul smell is the most common sign of a bad catalytic converter. If you smell what seems to be a rotten egg and it gets stronger over time, the catalytic converter is not working properly. A large drop in your fuel economy may be a sign that your catalytic converter is going bad or is blocked. A lack of power, especially at high speeds, may be a sign that the catalytic converter is going, or has gone, bad.A vehicle that stalls during idle, or idles rough, may have a blocked or bad catalytic converter. Your catalytic converter may be blocked if you experience bucking or hesitation while trying to accelerate. Additionally, your vehicle may run at a higher than normal temperature. A catalytic converter typically doesn't go bad without an underlying cause. A mechanic should be able to find the original problem and may not have to replace the converter.
If a car is sputtering at low speeds when driving one thing it could be is a clogged fuel filter. Another possibility is the catalytic converter could need replaced.
It could just be the heat shield on the under side of the catalytic converter.
maybe the catalytic converter?
Previas have a history of a whining noise coming from the catalytic converter. There is a bracket inside the converter that when loose or has came apart creates the whining noise during acceleration. It especially is very pronouced during high speeds in the freeway. You might be in for an expensive cat converter replacement.
You have a malfunction in the emissions system that becomes harmful to the vehicle when driving ( engine at higher than idle speeds ) You should get it checked asap. It quite often ( as long as it seems to be operating Ok ) an issue with misfiring that can cause the catalytic converter to overheat.
my first guess would be that it is your catalytic converter is plugged. Also,check the oxygen sensor. Also, the IAC (idle air control) may be at fault.
why is my 1991 Mazda truck surging at higher speeds
Higher g's produced at higher speeds are harder to survive.
Because your motor is spinning faster at higher speeds causing higher rpm's
Because at higher speeds you have more velocity than at lower speeds transferring more energy to make a bigger crashing causing more damage.
Slippage in the transmission or a bad torque converter