The car idles very smoothly, the engine makes rattling sound during shifting when rpm exceeds 3500. Another question, Engine kind of vibrates when i release the accelerator (without applying brakes) around 70-60mph. Does this mean i need new timing belt?
you went from about 5 million things it could be to 1 million things it could be. could be any number of things from leaky injectors, bad IACV, dirty throttle, any of the emissions equipment, not to mention transmission and driveline issues.