That cable won't fix your problem...but sounds like it needs doing anyway.

Need to adjust the idle governor to solve the idle RPM (most likely...)
The idle knob cable just pulls on the accelerator linkage, and can lead to the engine semi-running away. The engine when cold needs more fuel to idle right, when it does warm up that excess fuel causes it to rev up by itself (as my neighbours have found out a couple times ) as the accelerator "over-rides" the idle governor.

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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD