aProgDirector is correct. Programs want to know that their candidates will be ECFMG certified, especially when its a relatively competitive field like General Surgery. You are required to have completed all the steps toward certification by date of submission of your Rank Order List, with the exception of your final diploma.
I agree, it is *highly* likely that the reason you didn't get any interviews is that programs are increasingly looking for applicants who have completed all the steps toward ECFMG certification, with some even requiring certification to interview. They are unlikely to interview someone who has quite of bit of work left toward certification with the attendant risks of matching someone who cannot get certified and therefore, cannot start residency. Unfortunately, it appears you didn't know realize this or underestimated its importance.
Like aProgDirector, I'm afraid I cannot offer a definitive answer as to whether its better to take a Prelim position in the scramble or to stay in Ireland for another year. But as he notes, there will be some logistical issues...will you be able to get time off to come to the states to interview? Depending on how successful your application, you could need two months available to interview. In addition, a Irish intern year usually follows the British system of medical education in which you will have very little surgical training (ie, it will be akin to a rotating internship), so the experience it offers to PDs evaluating your application would be minimal. The major advantage would be if you were interested in ever returning to the island to work.
Thus, I really see little value in staying in Ireland except for the last reason above. Step 3 is not likely to give much added value to your application. MY recommendations would be:
1) be in the US for the scramble. The scramble is very difficult, psychologically and technically. Trying to do it from abroad is even harder. Programs may wish to meet you in person. You'll need access to a FAX and a good phone and internet connection.
2) do some research into programs, trying to find ones that have a history of taking a prelim into their categorical track. I know ECSU and Penn State both have such a history; others surely exist.
3) if you find a program which has a Prelim position available in the scramble which interests you, take the position with the knowledge that it will be a nearly year long audition rotation. Expect to work MUCH harder than you ever have. Start working early with your PD regarding potential positions for the following year - either in your program or another one. Bear in mind that academic programs tend to have more flexibility in regards to offering a position because of the lab/research years.
4) if you don't find something in the scramble, I would still probably recommend you try and find some research here in the US unless your internship year in Ireland really will afford you time to come back to the states for interviews (and you can afford to travel back and forth or stay here for a couple of months). As noted, since applications are accepted in September and the deadline for Surgery programs is October 15-November 1, there isn't a lot of time to impress faculty, so you have to start running on July 1.
Next year you will be applying with ECFMG certification and some US experience which will strengthen your application greatly.
I wish I could give you definitive answers, but there are no hard and fast rules or universal truths about this issue. Finally, please be aware of the IMG/FMG surgical "trap" - the American Board of Surgery no longer accepts applications for Board Certification from residents who have trained in more than 3 programs. Therefore, you do not want to be the resident who jumps from program to program, continuing as a Prelim rather than being offered a Categorical resident. I have no doubt that some programs take advantage of IMG/FMGs this way, especially as surgery has gotten more competitive and applicants are more desparate. Thus, you need to consider a Plan B as well.