First of all, this car finally runs fairly well. I have taken some fairly long trips and haven't had any problems.

Performance wise, I don't have near the same amount of acceleration as I once had (but the TCV was connected backwards no signal). When driving, the transmission doesn't seem to lock up and the rpms go high, but not much power until 4000. It requires WOT for decent acceleration.

I have no CEL, nor have I seen it in a while. Can the following components fail and not have a CEL? Catalytic converter, O2 sensor, TPS, transmission solenoids.

I have never cleaned the throttle body. Is that very difficult? Maybe I should do that next?

Bonus question: On a recent trip from Columbus, Ohio to Chicago, I noticed a constant scraping/screeching noise coming from my brakes. I could hear it on the highway with the windows down and in the city at slower speeds. I did new pads and rotors recently. What might be causing that? I noticed a groove in the center of the rotor.

I appreciate any thoughts.
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1959 Volvo Amazon 121, 1998 Volvo V70R AWD

Cleaning the throttle body isn't difficult, just remove the intercooler hose from the throttle and spray TB cleaner and rub with an old tooth brush. Wait about 20 minutes to let the cleaner evaporate before putting the hose back on snuggly.

It sounds like you are not getting full boost. Check all of the IC hose connectors and make sure they are snug. My trick: using a shop cloth, grab a hose near a conntection and try to twist it, if it moves tighten the clamp. Also check for cracks in the accordian sections.
You should get full boost at around 3000rpm.

The tranny should lockup at around 50-55mph with very little throttle application. The rpm's should drop around 2-300 at lockup.

Recheck the vacuum lines at the boost controller.

Brake noise. Verify that the noise is from the front or rear. The rear parking shoes are known to delaminate and fall off causing all kinds of noise.

A groove in the center of a front rotor needs to be inspected by removing the pad and verifying that nothing is imbeded in the pad. If you have uneven braking issues, check the calipers. Your car is old enough to have a failed caliper. I assume your slide pins are clean and the pistons easily pushed back in when putting on the new pads.
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My back feels better when I sit in a Volvo seat