injectors could be sticking also, very common problem. I have been cleaning them with ease for years. You need 1 injector plug with however long wires you need with aligator clips on them. Connect 1 clip to ground and then tap one to power as trying to get the inj to open and close. have a can or 2 of carb clean with the small extension tube that comes with it. Spray and let it set for a minute (to top of the inj where the fuel goes in). You will notice the tube is almost the same size as the fuel opening. Keep taping the aligator clip to power and eventually you will here it click. Now leave it in the open position with power applied and spray inside the hole of the injector and you will start to see a spray pattern coming out of the inj. I actually had a small rig made to hold the injectors which applied power and carb clean. but you can do one by one by hand. works excellent with a little patience.