No Idea What to do anymore! Need Professional help..

I'm still having ventilation issues. I bought a new inline fan, the 4 Inch active air which is 165 cfms. My box is about 3'x3'x4', but as you can see in the pictures The lights are enclosed off to an even smaller area that all the heat is getting trapped in. So we finished installing the new fan today and we haven't exactly made the whole ducting air tight but it's still a pretty snug fit and my box still refuses to cool down! It's hovering around 93. Could it just be that my box isn't entirely air tight or that i need more passive intake holes. I made 4 passive intake holes all about 1.5-2" in diamater and was thinking about adding one 3" hole in the cneter right under the ducting. I really need to finalize this set up so I can shut the door and not have to worry about heat! any help would be appreciated.

165 cfm for what? 28 cu ft?

So like every minute you have exchanged the air in there more then 6 times.
Well whats the temp of the intake? seems to me thats what your dealing with.

I really dont think adding the 3" hole is gonna make that much difference but It wouldnt hurt. Cooling the intake somehow is what you need to do. Running your lights at night helps but nothing like fresh air. I cut a hole in the floor under my cab and get it from under the house.

the intake air is pretty cold. I got ac. I'm going to buy a new duct because this one is old and beat up and i'm just going to caulk all the connections then throw duct tape over so its all air tight. hopefully thats all i gotta do.

I'm not a professional or anything, but I had heating problems when I first built my cab and I tried a lot of things. Here are some lessons I learned.

The type of fan makes a big difference. I first bought an inline fan and i think it was over 100 cfm for a small area. No go, wouldn't cool anything down. Then I bought a squirrel cage fan, they are louder but work well. I got one rated at 500 cfm's for a small area to clear out the air better. There are inline fans that can do that as well and they are much quieter. So maybe a better or different type of fan might help.

The type of light matters. While everyone loves CFL's I noticed that when compared with an HPS they are way hotter. I had about 200 watts of 42 watt CFL's and they were way hotter than my cooltube 250 hps. So maybe a small HPS in a cool tube might be better. There are plenty of tutorials on making a DIY HPS cooltube. I don't know how many watts you are looking for but there's an HPS for every budget. I hate that I bought all my CFL's and haven't used them, but my temps are better off without them.

Type of air filter matters. Throwing one of these on there reduces air flow and causes temps to rise. I use Ona Gel near my exhaust now.

AirFlow matters. Look at (or feel) how the air is moving. If it is getting trapped somewhere then you need to move things around or possibly redesign.

Sorry if none of this helped, but thought I'd give it a go.

Oh btw, my temps were hitting 100+ and now sit at 78-82 all the time.

One last thing I did was to change to a night growing schedule which knocks off a couple of degrees.

Hum, I forgot to mention what I use.
I have a 48" by 24" cabinet that is 72" tall.
I'm using a 400 watt HPS with a DIY cooltube.

I use an 80 CFM whisper bathroom fan for the canopy and a 4in duct fan thats 120 cfm for the cooltube. With an intake from outside and exhaust blowing outside also I run my lights at night. My average temp in the winter is about 77° In the summer is 85° If I run lights durring the day add 10°