Extreme Shaking at idol!?!?
 

I have a 2003 ford ranger that originally only shook when I drove at around 70 mph. Over time the shaking got worse and seems to happen more often. It shakes the most when it is in park idling or when I'm at a red light. Enough to shake m whole body. The check engine light often blinks while this is going on. I recently replaced all the injectors which didn't really help the shaking it just helped a no start problem, I also just replaced all spark plugs with Motorcraft ones and the shaking seems even more constant now even after I changed the plugs. I cleared all codes which said I had multiple misfires and the check engine light started blinking again within 1 Mile after clearing codes. This has become really frustrating and costing me too much in such a shot amount of time. Any suggestions on what to check next or what the problem might be? Also when I accelerate it drives okay up till about 55 mph the it shakes bad and if I lt of the gas it goes back to normal but when I accelerate again it continues to do this unless I go above 65 or below 50. Thanks for reading I would really appreciate any help.