The idle control motor sounds bad. It is adjustable (if I recall) on a 1990. It may be over adjusted and not fully functioning when cold. The ECM controls it; however, the part is nothing more than a solenoid. It either gets power or it doesn't.
THe code you are getting, 55, is a finish code that indicates the computer has gone through all its checks. If that is the only code you get, there are no trouble codes stored in the system.
Based on your problem, I feel the idle control motor is bad.
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Thursday, January 27th, 2011 AT 7:38 PM