my volvo wont go

I'm having big issues with my car not wanting to accelerate after being driven certain lengths of time or distances. It seems to be worse in the warm weather, sometimes gets better if I run the heater. Sometimes when it acts up and I give it a little nap, like 15 minutes or so, and it will go just fine again. But it really sucks when that happens to be on the side of a busy freeway. It hates stop and go traffic. I've taken it to 3 different mechanics and they haven't figured out whats wrong with it yet, the last one had my car for 5 days! I love my car and its in excellent condition otherwise (alot of new stuff), I just want to be able to drive it to work or even maybe just be able to sit through the drive thru without it going crazy on me. Does any one have any ideas what could be going on?

It would really help if we knew the year and model..

Ok, looked at your profile, 86 740. If thats wrong, let me know.
Here's a link for troubleshooting. But sounds like fuel pressure regulator related.

bricks (http://216.160.8.21/FAQ/700-900/EnginePerformanceSymptoms.htm)

Thank you for replying... it is an 86 740 turbo wagon.
I think you might be on to something and I'm going to talk to the last guy I look at my car about that.
Thank you again.

Let me know how it goes. Also, the early volvos have a notorious problems with relays. Poor solder joints. I would also pull the fuel pump relay, behind the ashtray, I believe its the furthest to the rear and left. You have to pull the cig lighter and coin tray out. Pop the case, and exaim with a magnifying glass, you can resolder. Your year group is also a victum of engine wiring harness deteoriating. But don't look for a new one, around $400. You can get a used one for under $200. I have an 85 740, original owner. I'm posting another link that has a wealth of info for 700/900 volvos.

Brickboard (http://216.160.8.21/FAQ/700-900/)