I have a 2003 V40 and on a hot day when I go to start the car after it has already been running (30 minutes later on hot engine start-up) the engine stumbles, hesitates, and stalls for first 5 to 10 minutes. The engine bogs when hitting the throttle (very poor to no throttle response). Then after the 5 to 10 minutes the engine gets back to normal. It is like something is having a bad case of heat-soak when the engine gets shut off on a very hot day and then clears once the car has been mobile for 5 to 10 minutes. Car runs and drives great on cooler days. Anything over 25 C or 80 F (not sure of the F conversion). Any thoughts???

 

Only a guess.
On switching off your hot engine the water temp /coolant system pressure rises whilst vehicle is standing resulting in water seepage into 1 or more cylinders due to a bad head gasket????
When you restart the engine it runs rough until the water is pushed out via exhaust and any further gasket seepage is prevented due to the engine cylinder compression being higher with the engine running.
Is there a whitish steamy exhaust smoke or quite a bit of water dribbling out of your exhaust pipe when you restart the warm engine and it is running badly?

 

Another thing to check into is your throttle body. My car (a 1992 240) has the same issues, and I'm going to clean the throttle body either Monday or Tuesday. Here's a link: How To Clean Throttle Body On S/v40 (1996-2004) - FWD/AWD 1999 - 2010 - Volvospeed Forums
Hope this helped!

 

Compression is good, no coolant in cylinders, level is good...thanks though.

 

T body is in good shape...