Labrador with Delayed gastric emptying causing acid reflux

Labrador with Delayed gastric emptying causing acid reflux.
Alfi is a 7 year old Labrador Retriver and has had these symtoms for few years, Alfie has had numerous scans, cameras, had a fluoroscopy with many different medications and food sugestions which none have worked. It seems to be worse in the early morning where he cant keep still has lots of lip smacking and pawing his ears face and licking himself, although worse in the morning it does happen all day just not as bad. I’ve been to the vets so many times but nothing seems to work.

He is currenty on Royal Canin Gastrointestinal Low Fat which i soak and put cooked chicken or beef on top. Just wondering if anyone here has the same problem and can suggest some foods i could try.

Thanks Daryl