I don't know where the smell is coming from but it last 8 hours most days. I have had the traps in drains replaced but did not solve the problem. It appears to get worse when there are high winds in the area, my family complains of headaches, issues with asthma already.I really need some suggestions, because we can't move so solving the problem is the only solution... please help if able.

we used to have a subpump in the basement for flooding before we got connected to the public sewer line

Are you sure that that pump was a sump pump for ground water flooding?
Could it have been a sewage ejection pump? A sump pump would not be a factor in converting from a septic system to public sewer, a sewage ejection pump would.

Hi Kelly and welcome to The Plumbing Page at AskMeHelpDesk.com You are responding to a 5 year old dead thread so I gave you one of your own. Please check the date before you post. Thanks So what have you got down there? A sump pump with a open pit or a sewer ejection system with a closed tank with two pipes coming out of the top?
Something you said caught my eye.
I the smell seemed to return on days of really high winds,
You could be getting some blow back down your vents. The solution would be to install vent caps,(see image) to prevent this from happering Also check the trap levels in the basement floor drains and fill the traps with cooking oil if they're unused. Good luck, Tom