Air filter size 1989 2.6L

I just bought myself a 1989 2.6 D50 and one thing I found slightly odd about it was the way the air filter is set up.

The previous owner had a tall filter in there that made the top of the can set about an inch higher. He said it's because his dad, the original owner, asked the dealer why the truck ran sort of crappy they said it was because the 2.6 has the same air intake as the 2.0 and couldn't get enough air, so to put a taller filter in.

My concern with this is that instead of pulling cooler air in from the front of the truck it's just sucking in the hot engine bay air. Also I noticed that there looks to be a spot from the exhaust shroud to the air intake that should have a hose as well but it's missing. With the engine just feeding off the engine bay air right now though that's a minor side issue.

What I'm asking is if there's any validity to the 2.6 not being able to get enough air with the stock air setup. I'm not looking to make this thing any faster, if putting a stock filter on there slows it down but gives me some MPG back then I'm fine with that, or even if it would just be better for the longevity of the engine to be pulling in some cooler air.

Thanks

Well, I switched back to a stock size filter. I think the problem may be that the carburetor pre-heater hose is missing. I'll have to source one of those. Does anyone know a good parts retailer for various bits like this or is it going to be one of those universal cut to length kits?

any universal cut to length hose will work fine

So upon changing back to the stock size filter I see what the previous owner was talking about. Under hard acceleration it does seem to lose power. There's room on the other side of the air can to open up another hole and route a secondary intake to the front between the radiator and the battery.

My only concern at that point would be that it would be a partial bypass of the carb pre-heater.

Anyone have any thoughts on the matter?