2000 Venture Miss ?

Our 2000 venture has just developed a miss, I notice it to happen when your going at a steady speed then you go up a incline slight or a hill it starts missing and sputtering, if you pres the gas then the van will take off and run fine..

anyone have any suggestions ?

Could be several things. Fuel filter plugged, dirty injector, bad spark plug or wire.
How long has it been since it was tuned up? How many miles?

well the engine has less then 100,000 miles and we just had it installed a year ago, it was running fine until, my wife had to sit in traffic for a few minutes, then when she took off it started sputtering, and now it sputters intermittently while driving, yesterday I noticed that when you start it, the engine idles rough for a few minutes, then seem to clear up some ...

I took it to my local Napa and they checked the code, (didn't tell me the number) but said it was something Catalyst Bank 1, Basicly the 02 sensor, she then told me to run some dry gas through it before changing the Sensor,

I already ran a bottle of chevron tech ron through it the van a few days before I took it there...

Anyone have any suggestions ??