300E Surges and dies

[Bill W. Rippy]

Help!!! I have a german 1985 300 E. They say its the same as 1986 US. Its a 6 cylinder fuel injected. It runs about 20 minutes then starts surging real bad upon acceleration, then it dies, completely everytime you just barely touch the accelerator. It will start right back up but will not move much if you have to press the accelerator. I live in Costa Rica and parts are VERY EXPENSIVE. I have replaced fuel filter, cleaned injectors, replaced fuel pump, and today the (Dosificadora) which is I think the fuel pressure regulator. Its the part that the fuel lines come out of to the injectors. New this part costs here $2000. Rebuilt $1000. I found a used one for $350. but when installed ...nothing ...no change. the mercedes mechanic feels real bad. But ???? I have read here about oxygin sensors, catalytic clogs and crankshaft sensors as being maybe the problem. I can't keep buying parts so really need help on what to do now. Its Friday night and I have an appoinment with my Baby and the mechanix Tuesday. I love this car.
Bill