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.

Power stage, ie ignition control module. Heat sink dried out???
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Post Back. That's whats makes this forum work.

When you say ignition control module do you mean this? https://onedrive.live.com/redir?resid=1B039ACD2AB01ADE%2165790 so I took this apart and its completely encased in a resin and does not seem to be serviceable.

I agree on the power stage. Here in New Mexico I have had the same problem. Get the heat sink at Radio Shack. I've had to do this job on three 240 autos. Seems like your getting ready for summer.

Thanks NewMexico240... Could you let me know what the part number is for the sensor that requires the heatsink? Yep, AZ summers can be rough I want to make sure everything is tip top. :)

"I agree on the power stage."

But, the car is a 1988, and should sport V/C ignition. The "power stage" for that system is internal to the ICU and not known for temperature intermittents other than a few isolated claims that a replaced ICU solved a similar syndrome.

The Hall sensor is a much more troublesome component, not that likelihood is the best answer as to which component to throw at it next.

If it were mine, I'd start wiggling the wires at the distributor connector and ICU at idle, which OP probably already has done, and then try to influence with heat gun. Of course, when the problem occurs, and the car can't be started, it would be a good idea to prove it is ignition or fuel by using some starting fluid. Side of the road. Still it might not be conclusive.
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Art Benstein near Baltimore

"If only Sweden awarded a Nobel Prize for recycling its cars." - General Colin L. Powell

My mistake....I did not realize the year of model.

Thanks Art Benstein, I've considered the Hall sensor this one https://www.fcpeuro.com/products/volvo-distributor-ignition-pickup-240-244-245-1237031292 correct? But the mechanic said that this fails completely and does not exhibit intermittent issues... would you disagree with that statement?

"But the mechanic said that this fails completely and does not exhibit intermittent issues... would you disagree with that statement? "

I would agree with the statement as it applies to the semiconductor that is the Hall-effect device. However, its implementation in 1980's Volvos uses small stranded wires leading from it to the connector on the side of the distributor which are known for shedding their insulation. The replaceable component includes the wiring. It is just one thing you have not replaced yet.
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Art Benstein near Baltimore

"Well, brand my terahertz DNA unzipper!"

I've never replaced one of these before. Do I have to take the whole distributer out to replace this unit.

Model yr 88 has the most rock solid fuel delivery system and ignition components. No CPS, power stage crap etc. Pull the vacuum line to the FPR and check for fuel. Clean the throttle body yet? where does the idle rest after warmed up? It can be adjusted rather easily.Miles on the car? Fuel temp sensor been replaced yet? You have done all the hard stuff so far.

Thanks! I have not cleaned the throttle body.

Here is about 1.5 min of how it sounds at idle... sounds good to me.
https://onedrive.live.com/redir?resid=1B039ACD2AB01ADE%2165792

when I bought it in 2011 it had about 135k on it. The odometer broke about 2 years ago and I'm sure it has over 200k

Where is the Fuel Temp Sensor located?