Fully rebuilt my engine but there's a misfire on cylinder 3.ive noticed injector 3 is blocked so I've ordered a replacement I'm hoping that solves the problem.if it isn't the injector what else could be an issue?
If the leads & plugs / injectors are OK ( you can check by taking the rail out and placing each injector in a jar, take dizzy off and spin dizzy with the engine ignition at run position (not start), each injector will fire. You can test spark/leads by unplugging lead and see if engine tone changes and then switch the plug/lead to another cylinder and see if the problem moves.
check the autodata files in the electrical FAQ and make sure your base ignition timing, co pot and idle screw is set appropriately, otherwise you will be chasing your tail
swap the injector for another and see if the issue moves, stays or now does it on both.