Changed the spark plugs, the oil filter, air filter, catalytic converter on both sides and ac vent accuator. For a while now the car would shake and sometimes cut off while idle. Then upon changing everything it was fine. Within the last 2 weeks when I turn the ac on it would shake like it wanted to cut off again. Today it started shaking so bad like I was being bumped at warp speed on all sides. The car wouldnt go over 20MPG. I barely made it home. The check engine light was blinking but wouldnt stay on. I have no clue what this could be. I changed everything I could find relating to the problem but now it seems it is worst then before. What is going on with it? Its a 4.7 engine with 198,000 miles. Is my engine garbage or can I fix it? I do not have thousands to spend for a mechanic to search for gold under my hood, But I need my car.