Still investigating rough ilde until car warms up to about 60-80C Not as bad this morning even though it was 19 F degrees.

1. Would a "bad" tank of fuel be more noticeable in cold start than when fully warm?

2.Would fuel pressure regulator problem be more noticeable when cold?

Plugs, rotor, dist cap in good shape--rechecked condition yesterday.
fuel filter replaced this year.
New OVP and water temp sensor

Cleaned idle control valve and if I disconnect it engine revs increase so I don't think this is a problem. Wasn't very dirty either

Frequency valve buzzes so it appears ok.

Cannot find any vacuum hose problems.

Filled tank up yesterday and rough cold idle not quite as bad but it still somewhat rough till warm then car runs and idles like a dream.

Haven't checked cold start valve yet but it seems if this was a problem car would not start right up and run at higher rev abouat 1000/min then gradually drop to normal 500/min when warm.

thanks

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95 E420 ( 76K) SOLD
85 380SE(125k)
95 SL500(72k)