Trying to fix stalling/chugging problem

Hello people,
This is my first time posting on this site so I realy need some help. My car a 1995 Grand Prix SE 3.1L engine sometimes stalls out. Some times I can start the car and drive fine. Other times I cant get the car to stay running. When the car stays runing I can drive fine until I stop at a stop sign and turn right and accelerate and the car chugs and wants to stall out. I finish the turn and straighten my wheel and the chugging stops. I turn left and the car dont chug at all only when I stop and turn right while accelerating. I had the car stall out on me at an intersection and had to push it out to a side road :disappoin. I tried to get it started on the side road and sometimes it stalled out, and other times I got it to stay running, but when i put it in drive it stalled out again. I had to have my dad come and help me tow it home. I've taken it to a mechanic shop and had them work on it for 5 days now. It even stalled out on them when they test drove it and they had to tow it back to the shop. If there is anyone that has has this problem before or had something similar happen to them let me know. They gave me a call today saying that that cant figure out whats wrong so I dont have to pay anything for the time they had it. Ohh I changed the fuel filter already and it still does the same thing. I've tried dry gas and fuel injector cleaners as well. If anyone has any other ideas lemme know please.
Thanx,
Jerry

Start with the fuel pressure. Tape a fuel pressure guage to the window and take it for a ride. Watch the guage when the problem happens

Look for a collapsed fuel hose.

thanks for all the input people but I found the problem. It was the wire going to the crank sensor. It was burned and the wire was exposed. I dont know if it was grounding or arching on itself not sure, but that was the problem. But now I got another issue. I only test drove it on side roads so when I thought it was fixed I took it to work. I was on the express way when I noticed that the RPM's where abnormally high and found out that the car wont shift into overdrive. I was going 60mph on the expressway with my RPM's in the 3000 range. Any ideas on what they did to it?? any feedback would be greatly appreciated.

Make sure your transmission has enough fluid. Do you have an over drive switch? Some cars you can lock out the overdrive.

ok I checked the trans oil and thats fine. going under today to look for the switch around by tranny.
thanks for the quick reply guys
ohh and btw anyone have any ideas about getting scratches out of clear coat my wife put a laundry basket on top of the car and it scratched it a little.
Again thanks a ton for all the input guys :) You've been very helpfull :)