you bet half the pot on the flop. not enough for these kinda guys. i bet 2/3-3/4, b/c i'm not interested in juicing them for value, i KNOW they'll call once in awhile, and that's my value.
when the A came on the turn, you should have been nervous. you say he never limps with an A. he didn't! he called a big raise from you. he could have easily done that (knowing his type) with A2-AK. a different type of player might reraise AK, but not a station. so then you bet 1/2 the pot again when the A hits? now, if it were me, I might just call (as opposed to raise) with AK. you're trapping yourself with that bet, methinks.
on the river, even though you "knew" he had the river, i might call too. he was betting 1k into a 4k pot. at that point, it's hard to let go.
now: how do i play these guys?
HOH1 is all about this type of situation, IMO, and he really changed my POV about bad players. here's the thing: these guys are unpredictable, and they act in illogical ways. so let's pretend it doesn't matter what the logic to calls/folds are. let's pretend he flips a coin to decide. YOU SHOULD LOVE THAT! the reason why is that as the bettor, you control the odds he'll be receiving. in this case, with a station drawing against you, you can offer him odds that aren't favorable to his draw (you did this just fine, btw, just not in as forceful a manner as i'd prefer to do myself). when he called you PF, on the flop and turn, he made huge mistakes each time.
over time these mistakes will cost him dearly. in the short-term, he'll bust you once in awhile. as a bad beat, it's kinda ho-hum

. as a "how to play this kind of guy," it's valuable and important in the extreme, imo.