Hard starting and runs rough on humid days

[bonz32]

HI,
I have a 1990 chevy lumina euro 3.1.As stated in the post title humid days are the only problem.In the good old days I would says distributor and cap but since this car doesn't have it am I going the right direction by thinking the coils?I put this motor in last spring.It had apprx. 82,000 on it.Thanks in advance for any input.
Jeff

[DR GILLES]

You Are Right About No Distributor But Their Are Ignition Wires On This Car An Easy Way Is Open You Hood In A Dark Area Or Outside At Night And With A Spray Bottle Water Down The Ignition Wires And Look To See If You Ca Locate Any Sparks You May Have To Rev The Engine Up A Little Like A 2000rpm Thats Were I Would Start Good Luck