print quality on flat vs taller objects

I have a prusa i3 and while I know the quality is not amazing I have noticed a certain flaw with the printer. On objects that are relatively flat with a large surface area the quality of each print is really good, but as my objects get higher the quality seems to get down. Especially on areas where the height is a few inches up and the layer is rather small. I know that for very small prints you need to print multiple copies because the plastic does not have time to cool. Is this something similar where prints that are relatively small, but not super small also need greater time to cool. Would I need a fan to fix this issue or is it something else?
Thanks in advance

A fan is a good idea. Printing taller parts brings out the short comings of inexpensive printers. Alignment issues become more apparent.

Also try a sacrificial tower alongside the object you're printing to allow the layers to cool. And print slowly on small layers ie layers that only take a short time to print.