my dd (3.6) is the same. she has no trouble chewing, but can't blow (but can also accurately name a dozen dinosaur types, so no problem with articulation). She did recently learn to suck, and is now good at drinking htrough a straw.
She can pick up raisins and cheerios, but can't pick up puzzle pieces without "raking" them, or pens either.
It is the same across her whole range of skills too. We were recently at BIBIC, and at the end of the assessment, there was not a single category on the score sheet where you could say she was proficient, but in each category her skills also outstripped her age (eg for language, she has a range of elements right up to 6+ years, but cannot ask for a drink). As mentioned before, she can name a whole range of dinosaurs, or sea creatures (angel fish, walrus, lobster, dragonfish) but could not name a hairbrush or shoes when asked.
She stunned her portage worker yesterday, as dd does not normally engage very well with her, and then she turned round, started rooting through the bag of tos, bringing out box after box and saying "what's this? what's inside? let's have a look" and I swear if she hadn't known that dd is ASD (and had it proved repeatedly over the last year lol) then she would never hve believed it on yesterday's performance.
It is really fascinating. It's as though dd can, at times, pull enough together to do a reasonable facsimile of normal,l but most other times she just can't pull it off.