timing problem
 

i have 1987 f150 engine 302 fuel injected i have a miss some where that i can't find at idle. hook timing light up disconnect spout wire timing is perfect at 10 btc than reconnect spout wire timing adjust to 20 btc than the missing starts timing starts to jump around so does idle. truck drives find off idle no misses at all. heres what i've replaced so far disturbutor plugs, wires,oxy sensor,air temp sensor, temp sensor,throttle position sensor, idle sensor, coil,control module, map sensor now these are the things i've check egr valve good, no vacuum leaks also replaced brain still has the miss and idle problem. brain came from junkyard. alittle more info the timing light will jump to about 30 than down to 10 than may go away for a few minutes than jump around again along with idle. off idle this truck will haul ass no problems