Volvo: 1994 volvo 940 help please, volvo 940, couple gallons

Question
hi everybody i have been reading through these post alot recently, had my 940 station wagon for some time now and recently had a lot of work done under the hood so i would like to hold on to it for as long as possible.  The problem im having has been going on for some time now, it happens when i am driving on the highway or when i come to idle after driving the rpm will jump eradically, when im on the highway it dosnt cut as long as i keep on the gas then there is a delay like its working up the power to get the gas out and all of a sudden the pedal will hit the floor and i will start flying, when i get to a light typically i have been having trouble idling the rpm will jump up and down and then just cut out, sometimes starting right back up, other times like last night when it cut it wouldn't come back on then this morning it did but a few min later cut out at a stop light and then alomst every time i pulled to a stop, but it would not turnover as easily this time, i had to pump the gas alot and then it would rev it alot and i would just have to gun it to try and make it home(horrible way to spend the end of my birthday btw...)  I recently had my fuel pump changed thinking that it may be my problem, when i left the shop the car ran better but still kind of had the same problem ,went back and we tried changing out the cap and wires to no avail.  the car ran perfectly for like a day, after that then the same problem, i spoke with him again, the only thought was that i had water in the fuel tank, and that i should use dry gas, he recommended running the tank to almost empty and then pouring like 3 bottles of drygas in and a couple gallons then taking it for a ride.  but since then i have been trying to empty my gas tank but the lower it seems to be going to more severe the problem seems to be i may be reading to into some of these things or not enough into something.  can somebody please help i love my car and want to know how to make it better in the most affordable way possible..

Answer
Colin,
Most times I see a vehicle where the problem is with less thatn a 1/2 tank of fuel the problem is in the in tank pump. It might be inop or the hose that connects it to the tank unit has come loose or is broken. I have enve seen a few where the in tank pumps works fine for a minute or so and then stops.
If all that is in good order you need a shop that will take and drive your car long enough so the problem will show up and the tech can make some tests and checks.