You definitely need a lawyer, no way around it. Plus it doesn't matter if you pass the field sobriety or not, or even if you are under the legal limit, if the officer believes you are driving impaired he can still write a DUI becuase he feels that whatever amount you had was enough to impair your driving.
At least you were smart enough to tell them you did not consent to them searching your vehicle, they can BS you however they want but if you stuck to it the evidence shouldn't hold up in court.
Also if you are drunk you should never take any kind of breathalizer test. Without it they have no proof you were drinking and without evidence they can't do much. That is why they started passing laws about taking your license away if you don't take one, becuase people who refused and got a decent lawyer always walked out of court without anything.
I think all you have to do is show them your license and tell them your name and then you have the right to remain silent. That is the best right you have, don't say anything, a lawyer can help you out if you don't say anything but anything you do say will be used against you in a court of law. Most cruisers have cameras now, so if you fall down drunk or start screaming with slurred speech that will be enough to convict you without taking the test. If you act cool and just get in the cruiser and don't say anything you can usually get off and if you have a good lawyer you might not even lose your license but I'm not sure how tight they sealed that law up.
I'll have to find it again, the Hell's Angels have a card they hand the police when they get stopped basically stating they know their rights and they will remain silent and if they are not being arrested to let them know so they can be on their way.
Most officers want you to believe they are on you side to help, they even taught you that in school, in reality all they are doing is collecting evidence to use against you in court.
Even in interagations they use tricks to if you just agree with them on a certain question is the same as giving them a confession. They are tricky and it's best to keep your mouth shut and let a lawyer do the talking for you. You can get out of a lot of things if you use the right to remain silent. When they start beating you or using a taser to get information out of you it's a different story and even those confessions hold up in court.
Never ever admit to anything, if you do and aren't guilty it will still hold up in court, even if they beat it out of you, I know they aren't supposed to do that, but they usually do whatever they want and you pay the consequences.
Always remain silent. A lawyer can save you butt more often than not if they have no evidence.