Low speed CD-RW media will hold the speed down, but CD-R does not have a "set" speed, though the drive may enforce a speed related to the code.
If the softwre is only offering speeds that are bad for the drive/media combination, it may be a software issue.
On blue dye media, can you see the difference between the burned and unburned areas?
I'm thinking, "it's had a good life, let it rest", a new DVD writer will probably cost less than half what that drive did, and a CD-RW drive will cost less than a CD-ROm did not so long ago.
4 years and a lot of burns, or 4 years and used as a general reader/writer, would be a reasonable life for a drive - cleaning might be a possibilty, but effective cleaning without damaging the mechanism is not an easy task.
Most "cleaning CDs" are either useless, risky, or both, only worth using as a kill or cure, as they can derange the lens suspension.
In the long run, one certain that configuration or software conflicts are ruled out, it saves a lot of aggro to treat the entire drive as a replacable component with a limited lifespan.
I believe the main failure mode is the degrading of the optical path, only some of which can realistically be cleaned.
The laser diode will degrade with use, but that is very gradual