surging issue after catalytic converters were replaced

surging issue after catalytic converters were replaced

hi Scotty, happy thanksgiving!

My car is Ford Transit Connect 2012 with 90,000 miles.

Weeks ago, it had a severe acceleration problem - turned out the 2 catalytic converters & the muffler were all plugged up (as described by the mechanic), so I got the 2 cats replaced but the muffler is currently disconnected - it was not too noisy without the muffler and I didn't spend extra money for something arguably not essential for the performance.

After the above replacement, the car runs okay but I've been sensing rather subtle surging of the vehicle. I cannot feel it when driving over 50mph, but I definitely feel it at low speeds. Also, idling is kinda rough.

What do you recommend? Also, do you recommend replacing the muffler ultimately?

Thanks as always.

No. 1-1


change the muffler first, the computer system needs it to run correctly