Open air cleaners?

[my 85 gmc]

Last summer I added an open air cleaner with a K&N 4 inch air filter to my 85 GMC pickup which has a 305 LE9 engine.
The question I have regarding this modification is it seems to make the truck sluggish in town when the weather is hot has anyone else noticed this(or is it a figment of my imagination)?
To help cure this problem I reinstalled the factory air cleaner which also has a K&N air filter, removed the door from the snorkel in the air cleaner assembly and opened up the air inlet snorkel in the rad support.

Thanks Rob

I guess this is a poor man's attempt at ram air!

[79BIG10]

Sounds like you need to richen it up on the fuel mixture. When you removed the air door you increased the air flow into the carb. Richen the air/fuel mixture and see if that helps.

[Prerunner1982]

ALSO, when you removed the stock cleaner assembly and shorkel, you removed the cold air intake. so now when its hot, the heat off your engine is heating the air going in your engine. engines run better on cool dense air...



EDIT: ok i typed that then re-read your post. when you replaced it, did it help? if yes, then obviously that was your problem, and if you want more air.. then heres your answer..