Help rough idle, hesitation

I have a 97' Express van with a 5.7 liter and it has recently developed a pattern of turning on the service engine soon light on after 2-3 days of rainy wet weather and it runs rough after I start it up in the morning and it hesitates for about 1-3 minutes of driving then it smoothes out and it seems ok until the next start up, if it has sat for a while, Then after about 3-4 days of dry weather the light goes out and it runs perfect, anyway the codes are for the B1 S1 o2 sensor, It has been replaced recently but it keeps coming up on the code reader, the plug wires are fairly new and the plugs are new, I tried to squirt everything with water while it was running but it did not do anything, any suggestions? thanks

If that engine has a distributor, I'd check the cap and rotor for corrosion. The problem certainly seems like it stems from a high tension ignition component.
How many O2 sensors does the engine have?

I replaced the cap and rotor ( I forgot to mention that before) they are brand new, It has 4 sensors, 2 on each side, I had to replace those allready within the last two years and the 4th one more recently, I have'nt had any problems (codes) from the other 3 sensors.

I think the next step might be to check the plug wires. Try misting them at night in the dark with a spray bottle filled with water. Look for arcing. You didn't note the mileage, but I'd bet at 9 years, the wires are pretty well fried. In your place I'd change out the wires next.
FWIW
YMMV

I have a 97' Express van with a 5.7 liter and it has recently developed a pattern of turning on the service engine soon light on after 2-3 days of rainy wet weather and it runs rough after I start it up in the morning and it hesitates for about 1-3 minutes of driving then it smoothes out and it seems ok until the next start up, if it has sat for a while, Then after about 3-4 days of dry weather the light goes out and it runs perfect, anyway the codes are for the B1 S1 o2 sensor, It has been replaced recently but it keeps coming up on the code reader, the plug wires are fairly new and the plugs are new, I tried to squirt everything with water while it was running but it did not do anything, any suggestions? thanks

What is the code no?
What brand/kind of plugs are you feeding it?
MT

Hi, I'm sorry, I guess I need to be more specific with my descriptions of the problems I'm having, I actually tried spraying water on everything in the dark and did not see any problems or did it cause the conditions I was talking about,( rough idle, hesitation) Also the cap and rotor is new and the plug wires are new AC delco and the plugs are new Bosch Platinums, as I described earlier it has been pretty dry around here for a few days and the motor is running great now.

Hi, I'm sorry, I guess I need to be more specific with my descriptions of the problems I'm having, I actually tried spraying water on everything in the dark and did not see any problems or did it cause the conditions I was talking about,( rough idle, hesitation) Also the cap and rotor is new and the plug wires are new AC delco and the plugs are new Bosch Platinums, as I described earlier it has been pretty dry around here for a few days and the motor is running great now.

Pitch the bosch plugs in the trash can and get the right AC Delco plugs for it .
It is never going to run right untill you do.
Run a search on Bosch plugs and you will see.
Lot of post on AF about how much trouble they cause.
Good luck MT

Well I was wrong about the plugs, they are AC Delco plugs

Well I was wrong about the plugs, they are AC Delco plugs

What is the code no?
MT

I believe it is PO135 but I did not see it the last time the code was read at the service station.

i have identical problem with my 96 1500 5.0 conversion van any luck i get po132 code

Well I was wrong about the plugs, they are AC Delco plugs

dont worry so is MT about the Bosch plugs...:sarcasmsign: