420SEL High Idle/Cold Rough Start

[jrhodes]

Hi, first time here, but hopefully someone can help.

I bought a 91 420SEL. The problem is that on the first start of the day,
it doesn't seem to want to catch, just turns over and over until finally
it fires, then takes a while to get running. Once running it idles higher
than it should.

Starts fine if it doesn't have to sit too long. Starts easier when the weather is warmer, takes longer when weather is cold.

I've been told to replace any number of things from the oxygen sensor,
to ignition sensors, to it's a valve problem.

Simply want an idea of what is the most likely culprit, don't have cash to
experiment with solutions.

Any help is greatly appreciated.

Thanks.