If the problem arose before removing the spring, then that would indicate the spring had already failed and it is still inserted in there and not doing its job. So you need to go re-examine it and see if it's in the right holes, or if it's cracked. The RD has an unmistakable orientation. If you put back the spring and the pulley arm isn't tight to the main body and does not require strong fingers to pull down, then the spring is not working for you and that's still your problem. The chain is a secondary issue.

I'm not saying that the chain might not have caused the issue, because cross chaining with too short of a chain can bust up RDs and snap the spring. So you may need to fix multiple issues: a) you cross chaining, b) lengthen the chain, c) RD pulley arm spring.