I put a new amp/speakers in my 91 F150( 300 I6). When I started it up it idled/ran terrible. I found that I cracked the hard vac line going to the EGR. Fixed it and it idles better but still hesitates/bucks when driving/accelerating. Hits a flat spot around 1800 rpm. I checked for other vac leaks and couldn't find any. Cleaned the EGR, TB, air filter is fine. New plugs/wires/cap&rotor in the fall. Is there something else I should be looking for?