Car turns over but won't start

A year ago, my grandson was playing with my key and broke off a half inch (only key I have). Surprisingly, the key still worked fine for the past year. A few weeks ago after several normal starts, all of sudden while the starter turned over as normal, it appeared it was getting no spark and would not start or even sputter.

I sprayed starter fluid in the mass air flow tube and it started and ran for a few seconds. I did the a few times and it started each time, so it is getting spark. I then checked the fuel pump and it is delivering gas. What it is not doing is getting any injector pulse.

My question is; can this lack of injector pulse be a problem that is being caused by a faulty key? I had been using this as a work truck and mechanically it was working fine, cosmetically it is in poor shape and not worth spending a lot of money on it. My dealer wants around $400 to give me a new programmed key which I would pay if I new for relative certain, the knew was the likely problem and not the computer. What I don't want to do is to buy a key and then find out it also needs a computer or other expensive item costing more than the truck is worth.

I can get a "valet" key from the dealer for about a third the cost of a new full function key, and since one of the doors can't lock anyway, I could live with just using the valet key and if it turns out the key is not the problem, not so much cash wasted. I have read on the Internet that as far as starting and running the truck the valet key works fine. Just doesn't give the locking features. Is this true?

Any help would be appreciated.