i have a problem no one can figure out,have had 2 dealers,2 computers and 6 mechanics try and everyone is dumbfounded.97 grand prix 3.8 nsc will randomly sputter and stall driving,idling whenever when it gets warm,may run fine for a month or two then do it out of the blue for a day or two,runs fine once it cools down,never throws a code.yeah know what u are thinking so wait a minute.here it goes.new battery,alternator,cam position sensor,cps,map,maf,iac,pvc,iat sensor,purge control valve and canistor,fuel pump,filter,all relays in car,injectors check to specs,new plennum,intake,lifters,whole top end done,head gaskets,cat,exhaust and new computer,all coils,icm,plugs,wires,entire cooling and ac system new,hoses,went thru wiring harness,yes new o2 sensors,tps,egr no leaks anywhere,vacuum is on he money,when car sputters have had fuel pressure guage on and it is fine,new fuel pressure regulator,everything,everything,everything is new,good parts no codes ever show and no one has a clue.no reason for this to happen but once it cools off its fine maybe for awhile,maybe a month so hey all advice is appreciated and if u fix i will send voucher for steak dinner,movie,bar tab,almost forgot new ignition wiring harness,speed sensor,knock and temp control sensors...all and every sensor is new