Omitting auxiliary "do" before "not" in coordination

Question

I was talking to a friend of mine and I came across this problem, I was talking to her and thinking that I should go meet her and not tell her that I would be going to meet her, and I said this:

1. How awesome would it be if I went there and didn't tell you about it?

And it got me thinking, if I had said:

2. How awesome will it be if I go there and not tell you about it?

It wouldn't have seemed as weird as saying:

3. How awesome would it be if I went there and not tell you about it?

So, I am probably wrong but it looks like when we talk about the present we can omit the auxiliary verb do and the sentence will still seem correct. Is this right?

I was just going over the question and I noticed that, instead of saying meet her and don't tell her about it, I said meet her and not tell her about it. Is it just me being weird, or is there something I'm not aware of?

Answer 1

You've got it right. You can omit 'do', but not when using past tense.

How awesome would it be if I go there and (do) not tell you about it?

Here, it's natural to omit the "do". Note that I'd still use "would" instead of "will", because you're talking about the [conditional] future. Alternately, you can use "don't" instead of just "not".

In your third sentence,

How awesome would it be if I went there and (did) not tell you about it?

there's a tense mismatch if you don't include "do", as without "did not" or "didn't" it automatically sounds like present tense.