My 98 classic is bogong Down really bad as I put the pedal down I just replaced the exhaust and o2 sensor

 

Does it stop bogging at wot?

 

it was running a muffler with no tail pipe and i installed a tail pipe now its bogging and having a rough idle

 

Which O2 sensor?

How's your tuneup hardware? Plugs, wires, distributor cap & rotor? Cleaned the MAP?

 

Weird. Could be coincidence. It's not clogged or crushed somewhere is it? Maybe you nicked an o2 wire in the install process? Your 98 has an in tank pump/filter assembly that may be worth checking out. When I checked mine it had all kinds of **** like leafs and sand.. Dunno

 

Having a similar problem with mine. Occasionally bogs down/sputters within the first couple minutes of driving it. It will clear right up if I mash the throttle so I don't think mine is a fuel pressure related. Replacing the post cat 02 today and I have a small leak in the exhaust that needs attention. No SES lights though.

 

Usually its the upstream o2 sensor that causes this problem. My exhaust system rusted out so I replaced everything including the upstream sensor even tho that part of the exhaust was still good. Right out of the box the new upstream sensor was bad so maps gave me another new one and that one was fine. While I had the first new sensor in the problems you are having happened to me. When it was cold it would bog until I mashed the throttle and spit and sputtered until the engine was warm

 

Cool. I'll replace the upstream one as well and give that a shot. Thanks!