My son has very similar speech patterns. The jibberish can be an entire conversation and he cannot make sounds within words that he can make alone. EI cuts off at 3 so I would have them evaluate him as soon as they can. After 3, you are transitioned to the school system under IDEA (the law). Depending, he may qualify for free preschool in your school district. I am not sure how you feel about your district, but we love ours and have nothing but cheers for the preschool team.
My best to you and your son
