85 supra engine troubles

[matthew87]

i bought this thing two months ago drove it 20 miles or so home ran great i went to start it it went to missing only hitting on 4 or 5 cylinders at a time never missing on the same cylinder all plugs are getting spark belive me there good shocked me every time never loses spark we pulled the tank cause the pump was whining real loud the top of the tank had a rust hole in it about the size of a dime the inside was nasty we changed tanks off a parts car i bought checked it was clean droped in a new pump put it on same thing so i changed the filter still the same sent a head changed out the coil tuned it up wires and plugs still misses what do i check now has a 2.8 inline 6