Husband's phlem is so bad and the PEP machine does not help. He is fine until we try to feed him pureed foods. He will still cough and choke.

If he has no push behind his cough then he is beyond the need of PEP. The next steps are torture: feeding tube, or suction machine. The choking on pureed foods means a change in medical status. How much more as a caregiver do you want to do? Will he agree with these treatments to extend life but not helpful to the quality of life. You want ideas from us but you need to speak of these changes to his doctor.

As per the other posters, I agree that this is a medical matter. Stop trying to administer food until a swallow evaluation has been carried out.
It may also be unsafe for your husband to take liquids if that's making him choke, as well. If that is the case, wet his mouth with a cloth, sponge, or similar.

This is a very difficult situation for you and your husband. Just do what you can to keep him comfortable. There really isn't much else that you can do.

Sounds like your husband is having swallowing issues from end stage Alzheimer's disease. Has he seen his doctor or Pulmonologist for this, and to let him know the PEP device is no longer effective? Maybe a call to him or her is in order. There may be a medication to loosen the phlegm rather than using the PEP.

You should look into hospice now because if hubby aspirates food into his lungs, it can cause aspiration pneumonia which can be deadly. Hospice can keep him comfortable as he goes thru this difficult time. I'm sorry you're both dealing with this situation.

Best of luck to you.

You need to have a swallow evaluation. This is ordered by the MD and will be done by OT, and can be done in his facility to evaluate his swallow. He should not be fed until this is done. The swallow becomes more and more week. Eventually you will have likely to make the choice between heroic and artificial ways of supplying nutrition such as tube feedings either by PEG implanted into abdomen or by NG tube put down for feeding OR the choice to do Hospice care.
Both an NG and a PEG are quite onerous, in danger of getting pulled out with sutures tearing skin or food dumping into the lungs.

At present, however, feeding someone with a poor swallow reflex (symptoms the phlegm you mention and coughing with feeding) is very dangerous. The symptoms you are seeing is indicative of good getting swallowed not into the abdomen but into the lungs. Pneumonia is the eventual result. Pneumonia was once called "The old person's friend" because it helped the aged slip out of this life.

Sorry for the bad news, but this is now a medical issue, and not an issue for advice from a Forum.
I would think that the care facility would have been WAY AHEAD of me in telling you all this. It is a very common problem with aging.