I have a now 16 yr old disabled non verbal son in a Boston public school. I have denied my sons iep for the past 2 yrs due to my son having food lodge in his throat for 7 plus hours, multiple times, and them having no equipment that was on my son's iep.  My question is it legal for the school to call dcf and have them threaten to take my child from me if I do not sign the iep the way the school wants ?

No, that sounds like retaliation. I'd seek an attorney. I know many parents say "I can't afford one" but when we're talking about choking, DCF and all that, you can't afford to not at least visit one for an initial consult.

Agree with Lisa that no, sounds like retaliation.  We don't offer legal advise on this site, but while you are searching for an attorney, as an advocate I would recommend signing the IEP but writing immediately below or beside your signature that exceptions/concerns to your approval of the IEP are attached - and then attach them.  It might give you more "legal pull" if your son is actually on an IEP.  For instance, you state above that they have "no equipment" that is referenced on the IEP.  That is not an excuse.  If it's in the IEP, they must obtain the equipment.  Once you have an IEP in place and they fail to implement, you can file a state complaint for failure to follow the IEP.  The IEP at least gives you a path and a way to try to get recourse.  Right now, you have nothing.  And the school district can say they "tried," but you refused to sign.  Let them try, fail, and then hold them accountable.

What is the school district doing now for the choking/food lodged issue is they have no equipment?  That would be my first concern.

Definitely sounds like retaliation. 

If I read your post correctly, it sounds like there is currently no existing current IEP?

It sounds as if one has been drafted and proposed, but parent did not sign.

To me, it sounds like medical neglect if the student has a history of food lodging in the throat and the school lacks the equipment needed, per a doctor letter that they have a copy of, to deal with this.  There are agencies that will look into medical neglect in situations like this.  Your state does offer facilitators for IEP meeting where they might help in getting you & the school on the same page.  Would the school agree to this?  https://www.cadreworks.org/cadre-continuum/stage-iii-conflict/facilitation/facilitated-iep-team-meeting-massachusetts  and https://www.mass.gov/info-details/facilitators-for-iep-team-meetings

Not sure if MA has a consult line that parents & advocates can call to help resolve situations like this.  I did find this group located in Boston - they might be able to offer guidance:  https://www.massadvocates.org/  I also found this:  https://www.mass.gov/info-details/education-resources