i people, i have a 86 jimmy. it had a 305 it it orginally, but the past owner put in a 350 at 85k. its now 141k and i'm having some werid stuff happen. i was just hit head on ,but the shop repaird the truck and said my engine was okay. i had just finished a tune up before the accident(same day to be exact) first of all.. i have a terrible idel even after adjustment, i just replaced my vacum advance and did a fresh tune up(everything). the distibutor cap is not in the correct position infact the mounting bolt is facing the firewall. i guess this has something to do with my timming being messed up. someone rigged my dist. so it would compinsate for the bad timming. so i'm driving around and i have a noticable miss in the engine at all rpm ranges ( even standing still). under load the truck runs fine, but as soon as you let go, its hell. also, when i'm accelerating i hear the flapping sound , like some peice of metal or plastic is hitting something thats turning. its almost like sticking a straw into a fan blade and hearing it hit.And to make it even worse, when i try to stop (sometimes) i will get 3-4 bad jerks comming from the the front of the car. the recent matinece i have had is... new u joints new driveshaft(s) new tires new cap, rotor, wires, 2 sets of plugs,coil belts feul filter. i took my truck to tuffies today because of the miss and vibrations. the guy checked everything out and told me about my distributor being wack , and he commented that it was something to do with timing. do you guys have any ideas what would cause... poor idel consant missing hard knocking when trying to stop flapping noise when driving i drive: 1986 Jimmy 4X4 brown and tan new 350 engine no rust 31 inch tires re-wired taillights (myself) i have bad vibrations!!!!!