difficult to cold start engine

[Qian Qian <qqian@pppl.gov>]

Hi, folks!
recently, I have problem to start engine cold in the mornings. It takes
three or four times to get the engine fired. I put on four brand new
spark plugs. the problem is still there without any significant 
improvement. I checked spark plug wires which still look like new.
 I had the fuel filter replaced two years ago. the engine
cylinder head gasket is leaking engine oil a little bit which I 
don't think has anything to do with the problem. what could be the
culprit?

Qian 85' 4000s(fuel injection)