Hey guys, got a question

My friend's son just got a 2006 Pontiac Grand Prix with a slight starting issue. It seems intermittent but it will at times start and then die. Yesterday I was told of the issue and I took a look at the car but unable to get it to duplicate the problem. I checked the battery and cables and saw a corroded positive terminal so I pulled the cable and cleaned the connection on it. I also disconnected the battery and did a load test on it. The battery tested good. Driving down the road the car runs good and has decent power and doesn't always do it so am unsure as to what it may be. I thought maybe fuel pump but it's not something that always happens so not too sure. Normally it starts fine first thing but after the car sets for a while (noticed after about 1-1.5 hours) it has issues restarting, and would start after giving it a little gas. She is going to get some fuel system cleaner to see if that helps but I'm unsure since it's intermittent and is fine afterwards.

The car has 158k on the odometer, and it's unknown as to the age of the spark plugs and wires. I'm going to check them out and replace them as needed but don't think that's the issue.

Any suggestions?