I did my own will in Florida when my husband passed. It is notarized and signed by three witnesses but no stamp. Is it legal in Jersey

Self-prepared Wills tend to have many "hidden" problems.  If you do not have money for an attorney (which may be less than you think), contact Volunteer Legal Services in your area.  If you have too much money to qualify for that, contact the local Lawyer Referral Services and ask whether they have a Modest Means program.  Note that without the notary's stamp, the document is not notarized.  This is just one example of the difficulties in drafting and execution which could make the Will invalid.