Acura cutting out fuel or electrical problem?

We REALLY need help. My son and I run a 93 acura integra on a local oval racetrack in WI and the car randomly just cuts out. We think it may have something to do with the heat, but not certain. The car runs great and then it just bogs out coming out of a corner and goes into an 'idle' for a little while and then comes right back to us, but by the time that happens, most of the cars have passed us. This is very frustrating and we need to start replacing things until it works. So far, we changed ECU, and installed a new fuel relay. The only thing that has been modified on the car is that there were 'slightly larger than stock' fuel lines installed and the head has been shaven 25k. I was going to order a Walbro fuel pump, but was advised that this would not be the problem?? (I thought maybe with the slightly larger fuel lines, maybe the 'stock' pump goes dry at times??) Could someone please let us know where to start with this problem? Thanks! TJ