Question: I came across the following example:

> 
> 大きかったり重かったりする本
> 
> 
> a big, heavy book
> 
> 
> 

I am not sure this sentence is correct to begin with, (part of me feels like it should be した) but assuming that it is, what would be the difference between the above and the following?

> 
> 大きくて重い本
> 
> 
> 

Both appear to me to mean "a big, heavy book".

I would also like to confirm that chaining adjectives unconjugated as follows is ungrammatical.

> 
> 大きい重い本　×
> 
> 
>

Answer: 
大きかったり重かったりする本 could be plural: some books being big, some heavy, some both. It does not make that much sense on a single book (unless the book is sometimes being heavy, and sometimes being big).
When multiple adjectives are equally applied to one noun, in most cases only the last one needs to be marked for tense, and all the previous ones can be left as plain adverbials.

大きくて重かったりする本 

If you do it with both, it will sound like that the two adjectives refer to two separate instances.