I've had my 2000 Volvo s70 (NON TURBO) (B5244S) for almost a year now, and every so often, like if I've been driving the car for over an hour every day it starts bogging down under higher torque/load instances. Like if I'm going up even a slight incline, or Starting off from 0mph, i can have my foot to the floor and it will only stay at the speed I'm at, have a really hard time acceleration, or go slower with my foot completely down.

I have videos of me trying to move past 35 and it won't go anywhere. I've replaced fuel relays, spark plugs, pcv/oil trap and I still have no idea what to do next. Any suggestions?
VIDEOS BELOW.

 

There are two issues that come to mind and it may be one, the other or both.

First, you may have a weak fuel pump where it has trouble putting out enough pressure and volume for higher speeds. When the pump is cold it is not as bad but as it warms up the pressure drops. Someone needs to do a fuel pressure test. I'm not sure if a 2000 model has a fuel pressure sensor that you can read through the computer data, I don't think that it does.

The second is a failing electronic throttle body. With 186k miles it is probably toast unless it was changed.

 

That's the sound of an unhappy engine. It's interesting to me that the transmission downshifts but still has no power. The engine sounds like it's laboring. In addition to Tony's comments above, check to see if your catalytic converter might be stopped up. It sounds like you may have excessive back pressure.

 

The catalytic converter has been removed. I have a catless exhaust. So I'll check fuel system and maybe replace the throttle body if that doesn't fix it

 

MAF also comes to mind. Why is the yellow arrow on the dashboard lit? Are you in Winter mode? Is there a transmission fault (light blinking) etc......

 

I have to say this - running without a catalytic converter is not only illegal is adds to the pollution problem. We all need to be individually responsible and do our part for clean air. I do not endorse any type of practice that disables or removes and emissions device.

 

​​​​​ I was in 4th gear lol