for your air mass meter (MAF, AMM, all the same thing) disconnect the cable and see how the car runs. if it runs crappy like it's doing right now, your AMM is gone and needs to be replaced. if it gets noticeably worse or displays new symptoms, then it's probably working fine. it's the thing plugged into your large intake hose.

knock sensor is located under your intake manifold below 2/3 headers. to check that, disconnect the wire and test it with a multimeter. the resistance between the 2 contacts inside should be about 5MOhms, so you'll need a multimeter capable of MOhms. it's kind of hard to reach down there, so you might want to consider just removing the knock sensor altogether (13mm bolt i think) and checking it on your table where it's nice and easy to reach. if your knock sensor is in fact broken, get a new one. make sure when you replace it you torque it down to the right amount of torque. too much and it'll be oversensitive, too little and it won't do its job. i believe about 13-17 ft. lbs. of torque is okay.

Note: actually, torque on the new sensor depends on whether or not you got one of the newer types or one of the older types. someone explained this to me before, where the new sensors have a wider range of torque, and the old ones are more nitpicky.
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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