Is this the '90 model from your sig? Or the '88? If it's a MASS AIR car, I would start by cleaning the element in the meter with some carb-spray. Then do the basics first, like plugs, wires, cap, rotor...and look at the TPS voltage. These simple things might fix it.
There is also something called a "Thermactor Air Bypass" solenoid which is picky about cold-starts. It's a little solenoid with a grey cap on it, located on the back side of the passenger-side shock-tower (see pic below). The little cap can be popped off and there is a foam-filter inside... it's glued down lightly, but you can easily take it off... blow the dust out of it with an air-blower and re-install with the cap back on. For some reason, if those things are dirty, they can cause havoc.
