Toyota Repair: Toyota Injections, oil change shop, spark plug wire

Question
My 4 Runner 95 started to shake when i back up. I thoung it had happen because it was cold so i stop and let it warm up. It happen again the next time i turn it on, and when i got to a stop it began to shake again, I thoung it might have been the oil so i check it was low but not as much, I put some oil, and continue to shake. I took the 4 runner to a oil change shop on the third day it was happening. They connected a computer to the truck, but i think they didn't know how to read the diognostics. They Did a run test and concluded it was one of the injectors that is not working. Because when is on low rpm's it would shake and when you get to higher rpm's it would stop. That was their explanation why it shake when you back it up, and when you would stop, and drive slow. The suggestion was to change all injectors, estimation would be $1300 for parts, they also thought it could be the caskets.. I was not too conviece what they told me..MY question to you does the diognostics sound familiar or close to what they told me.. It would help me out if you could confirm or give me other options what could be wrong with my 4Runner. Thank you Alan  

Answer
Problem with the injectors would be very unusual, it sounds like there is an engine misfire caused by another problem, you need to find a repair shop that can check the engine compression and check for a possible leaking headgasket, it could also be a misfiring spark plug or spark plug wire, it could be a lot of things so you need to find someone that doesn't say "maybe it could be this or something else" you may waste money and not fix the problem. I can't tell you exactly what is wrong because I would have to do tests that would tell me what's wrong, try to find someone that knows what they are doing, the oil change shop doesn't sound like it does.