Volvo Repair: loss of power, fuel pressure gauge, air mass

Question
I have a 1988 GLE740 with 455,000 miles.  After driving on the freeway for a 1/2 hour or so in warmer weather, acceleration is reduced greatly as experience after exiting the freeway.  Sometimes I can not get up hills.  If I turn the car off and start it again, I have full power as before I got on the freeway.  What needs to be fixed.

Thanks,

Dan Goldfarb  

Answer
Dan, This is impossible to diagnose without testing things on the car.  I can give you some ideas on what to check but you would need tools like a fuel pressure gauge. This sounds ignition related but like I said, I cant be sure without seeing the car.  It can be anything from a fuel pump check valve to the air mass meter.  Sorry.  Roger