I use a product called JIF-Action Contact Cleaner by GC Electronics... why, because that's what I found in my dad's garage

I'd assume it's probably available at local electronic supply houses since that's probably where he bought it.
Here's a web site that sells it...
The good thing about this stuff is that it has a silicone lubricant built in, so if you're cleaning a rotary control knob or something like that, it helps lubricate everything and stop future corrosion too. My dad used to swear by a stuff called "WISH" contact cleaner when he worked on televisions in the late 60s. I think those old knob type tuners were a big problem to keep clean...
For your injectors, I'd say anything that gets them clean (rubbing alcohol, brake parts cleaner, etc. especially if you use an old tooth brush would be fine. Then put a little dielectric grease on them to keep everything water and corrosion resistant.
Heath