You are right on the money when you suspect a fuel problem, but the culprit is most likely leakdown, often caused by a defective one-way valve on the fuel pump discharge side (although it can also be caused by the pressure accumulator, leaky injectors, leaky fuel distributor, or a bad pump, which will "stick and catch" when first engaged, until it has run for a short time). I don't know where this guy that's selling the car got his info from, but the only reason the CO adjustment might be a culprit is because he's screwed it up in the first place. If you want to mess with him, tell him it's the ignition assembly, then start it up on the first try by cycling the key to the "on" position 3-5X to cycle the fuel pump; if it doesn't start the first time, look at the fuel pump or relay. One-way valve is ~$30, but you will need a pressure gauge set to examine the residual pressures; the fuel damper/accumulator would be a good idea to replace as well.

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