won't start in heat of day

Having difficulties with my 97 chevy venture. Problem is, won't start in heat of day, have changed fuel filter, fuel pump, computer (twice) fuel relay sensor, coil pack, steering column, ignition, many many other things, any ideas??

Your going to have to give us a little more then "it won't start". How won't it start? Does it turn over? Do you have spark? Do you have fuel pressure? Do you have any trouble codes?

Yes it has spark and when running shows no trouble codes, when wont start shows no communication with computer.