I am looking for a way to send me an SMS text messages when emails are sent to me from a specific sender with a specific subject during business hours. I do not want to receive these text messages off hours nor on the week end. I was hoping that gmail filters or an IFTTT recipe would have a solution but I am unable to find any. Can you make a suggestion?
The short answer is no, IFTTT cannot do this.
You can have IFTTT send you an email. You can also send IFTTT an email to their email address. But you cannot have IFTTT monitor your email traffic.
I would try using filters on your email to highlight emails sent from this person with a specific subject, which is definitely possible - doing so on particular days is not possible though.