I have been having this problem for a while in my 94' turbo 850 wagon. i will be crusin at about 65 mph and I will lose acceleratiion in pulses. I tried shifting into neutral and revving when it happens and it seems fine. When the check engine light came on there was code for o2 sensor and knock sensor. I replaced the o2 sensor, and it was fine for a while. Now about two weeks later the problem is back and I have not taken it back to see if the o2 sensor went bad again. Could this be from the knock sensor

 

I could be possible that the knock sensor is bad.Did you replace both of the o2 sensors or just 1?Most of the time it is best to replace both sensors because when 1 goes bad it will make the other one go bad to.

 

I just replaced the one at the air filter. Where is the other one?

 

I just realized that when I asked for o2 sensor, he gave me the maf. where are the two o2 sensors?

 

The o2 sensors are in the exhaust system between the manifold and the front part of the muffler.You can't miss them they are screwed into the exhaust pipe with wires coming out.

 

I did research back to the quote I resieved from the volvo place. It was for replacing teh maf, and then the knock sensor. Where is that located and would that cause the hesitation. I put a bosch maf on there and the problem is still there.

 

The knock sensor is located on the engine towards the front of the car by the starter they are round sensors with screws going through the center.they are black and have a plug going to them.