mercedes c 250 d auto?

i have just bought a 1994 c250.d auto.today for £100.
when i started the engine the morning at the pre-owners home,the car started right away.when its idoling the engine shakes side 2 side.
i knew the pre-owner as we where taxi drivers.this car has been a taxi hence the 250.000 miles.he had been told it could be the elec-accelartor and he bought one £80 and fitted it but never sorted the shaking out.i took it to my brothers garage to do mot work on it and within 30.mins of driving ,it cut out 4 times when stopping at lights.when in the garage i lifted the bonnet ,and on the right hand side where the filter is housed ,one pipe that goes down under the filter seems to be leaking fuel,could this be the problem,also as you look at the engine ,at the back across the back there is a plastic pipe on the left hane side with what looks like a mini filter on the end of it and not attached to anything,and on the right hand side of the engine there is another plastic pipe that bends left to the back of the engine not attached to anything either
i have replaced one of the fuel pipes coming from the filter that had a leak today.started the car up and its still bouncing ,and when you rev it up,it cuts out,i spoke to the previous owner and he said he had it put on the computer and it found that the elec throttle was showing error codes,so he bought one cost him £80.and it was still bouncing around,he also said it had to be plugged back into the computerso the error codes can be wiped of.i spoke to a auto electrition today and he said it did,nt need it ,just disconnect the battery for 20mins and thatwill do.we tried that but still the same.