I got a 98 ext cab 5.2 4x4. Ive had the problem with accelorating and the ac/heat go to defrost. Now its stuck in defrost and wont switch. And every now and then i have a problem accelortaing out of the hole. it has a bad hesitation and seems like it wants to turn off until i come off the gas and lay hard into it. And apparently my new 02 sensor is bad. (bank one is in front of cat?) Any advice would be great

 

Do a search on wild vents.

Then do a search on Plenum.

You have more than one problem going on there......

 

did the plenum about two weeks ago. Ive read on the vents but ive never heard anyone with them stuck and wont switch. i can get the floor ones on and off just not through the middle anymore, I figure the 02 sensor might be giving me the problems overall. hoping its not the fuel pump filter regualtor

 

and i just found that the connector for the 02 sensor behind the bat was sitting on the cat and the connector is partly melted. Maybe that has anything to do with it?

 

Could be.......

You probably have a bit of a vacuum leak somewhere...... with the engine at idle, will the vents switch properly?

 

at idle i can switch to bi level. and to defrost and bi level/defrost.

 

I keep getting bank 1 sensor 1 heater cirtcut. Im hoping thats what is messing with my engine so i dont have to go in the fuel tank

 

Need to fix that connector, might solve your O2 code problems.

If things work the way they are supposed to at idle, you have a vacuum leak somewhere. Need to find it.

 

ive known about a vacuum leak. just wanting to make sure its not mechanical thats got it stuck in defrost

 

Fix the vacuum leak, and your problem will probably go away. (change the check valve too...)