Ranger won't start
 

I have a 2003 Ford Ranger with a 3.0 flex. It started with no problem but wouldn't run faster than 20mph. I replace the injectors now it won't start. What could be the reason?

You had better luck with your old injectors which likely were not bad. Put the original injectors back in and diagnose your engine systematically. Did you check fuel pressure? Fuel filter? Connect a scan tool, look for codes, at live data, fuel trims etc. You provided such little imformation that it is difficult to tell you what is wrong. Why did you replace the injectors in the first place? If it was for the reason you listed, you replaced one of the very least parts that would ever go bad.