2004 with 244,000 miles on it started to idle bad when stopped, push clutch in and rev engine to keep from stalling. Changed spark plugs, still runs bad. Put premium gas in and bottle of fuel injector cleaner and now it runs worse, have to give it gas to start it. Could problem be fuel pump or filter? Also now it makes a high pitch knocking sound.

 

Premium gas will do nothing to help out a poor running engine.

Stop by a parts store and ask them to scan for codes. Post the code(s) you get on here, if any. Give us the number. They start with the letter p and have four numbers, like P1234.