Max,
I know everybody is going to diss the Haynes manual,
But It covers 1976-1993
Page 4A-14
CIS Fuel Injection System/Troubleshooting

Symptom=Engine Idles Too Fast

A/Probable cause=Accelerator pedal,cable or throttle valve binding.
Corrective action=Inspect for worn or broken parts,kinked cable,
or other damage.Replace faulty injectors.
See section 12

B/Probable cause=Auxiliary air regulator faulty.
Corrective action=Test and if necessary,
replace Auxiliary air regulator
See section 12

C/probable cause=Air leaking past throttle valve
Inspect throttle valve and adjust,or replace as required.
See section 12

Section 12 is pretty involved,but descriptive.
At least these books are available at the auto stores.
Post back if you narrow it down,and I will tell you
what they say in section 12
I hope this helps a little bit,
Ken

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69-145-S ; 71-145-S ; 72-145-E ; 72-1800-ES ; 87-245-DL