I feel bad for my SS7. He is a good kid deep down, but he has some challenges, and I’m not the most patient person in the world.
My SS7 doesn’t talk very well. He mumbles a lot, and doesn’t enunciate well. He has problems with pronouns, tenses, etc. I recently started trying to correct him when he says things incorrectly, because if nobody ever corrects him it’s never going to get better. Sometimes he takes the correction and tries again. Other times it doesn’t go so well.

For example, a few days ago I was picking him up after work and I asked about his day. He said “incomprehensible I got incomprehensible I hide incomprehensible from Mrs. Smith!”
I said “you hid something from Mrs. Smith? “
“no, I hide it Mrs. Smith!”
“When you hide something but you did it in the past you say “I hid it”
“no! It’s HIDE”
“no, when you hide something in the past, like you did it before just now, you say ‘I hid it”
At which point he started pouting and whimpered “hide is a good word”

I know I should have stopped at this point, but I was getting frustrated too. “Buddy, I promise you, if you hid something today at school, the word you should use is “hid”
“I hided it!”

At which point I gave up, and he rambled for another block or two until we got home, but I couldn't understand.
I’m not really involved much with SS’s education and such, I mostly just make him dinners, make sure he doesn’t get into trouble while playing, etc. He’s in a special class at school, and I know they work on speech issues, but I’m sad and frustrated at my experiences at home. We have him every weekday evening and every other weekend.

Any ideas on how I can better constructively help? Should I stop trying to correct him when we drive together? Or should I keep up at it even if he gets frustrated?