1996 Other Saturn Models Acceleration problems

Engine Mechanical problem
1996 Other Saturn Models 4 cyl Front Wheel Drive Automatic

I have a 96 saturn sl1. The problem is when I hit the gas the rpm gauge actually goes down then when I release the gas it goes up. The car also dies when idling or just sitting to long when braking. I replaced the fuel filter, spark plugs and wires, clean the fuel pump. The car had suger put in the gas tank which I changed out fuel filter and cleaned fuel pump. A potato was also put in the exhaust which was cleaned out. The spark plugs was also tempered with which was also replaced so were the wires. Please help the dob2 doesnt work on the car so im having to go old school on checking things manually but I can only do so much without it and now im at the point where I have to buy and replace.