I have a 1988 Volvo 240 that has an issue I'm having a hard time trying to solve. This issue does not happen in the winter months. The car is in Arizona. During the summer months the car will stall when driving. I can tell when its about the happen as the car starts to lose power and usually 1-5 seconds after this it just dies. This stall has happened on the freeway at 55 mph, in the city at 35 mph and at idle. When it dies it does not want to start again. I have wait for it to "cool down" I can start it again and it takes me about 2 miles before it repeats this cycle.

I have done the following
replaced the MAF
replaced the Fuel Pump relay
installed new Main fuel pump
installed new In-Tank fuel pump
new fuel filter
I drilled out the catalytic convertor material
New coil
New distributor cap
New rotor
installed bronze fuses
I removed the temp sensor in the air filer canister and prevented exhaust pre-heat so it always getting fresh air
Replaced the fuel pressure regulator
New plugs
New wires
installed a new 25 amp fuse harness

I have taken it to a local mechanic but they are not able to duplicate the issue. This problem does not surface in the morning. It gets me to work and some days the problem does not surface at all; so its difficult to troubleshoot.

I'm out of troubleshooting ideas and hope some 240 veterans have seen this issue before.