99 silverado

so i have a 1999 chevrolet silverado ex cab pickup and just recently i've been having problems in first and second gears. when i go to put it down the truck hesitates and then rev's up like it wants to go but all i get is just back pressure out of the exhaust and no speed or little speed anyone have a diagnosis for my problem?

so i have a 1999 chevrolet silverado ex cab pickup and just recently i've been having problems in first and second gears. when i go to put it down the truck hesitates and then rev's up like it wants to go but all i get is just back pressure out of the exhaust and no speed or little speed anyone have a diagnosis for my problem?

REMOVE THE UPSTREAM 02 SENSORS...leave the holes open then test drive..if it runs normal the cat converters/exhaust is plugged...find out why before installing new cat converters...


this must be old body style 350 engine ....new 5.3L would have dtc codes etc...