92 gmc/350 hsp

frequently fails to start. weather makes no difference. service dept. did diagnaostic. replaced starter and started module. didn't help! Usually happens after sitting all night. May not start at first - several hours later it MAY? OR NOT! Fuel pump has plenty of pressure. Service people said tap gas pedal hit key and starts. Or, feather gas pedal and try starting. It is working so far but for how long no one knows but the shadow. REALLY NEED SOME HELP - USE IT FOR A LITTLE PLOWING.

Thanks

Rath: