Poor Acceleration when coasting.
 

1998 C230 Kompressor - From dead stop it pulls away OK. But if coasting and step on gas, it gets rough, check engine light comes on and it goes into "Limp Home Mode" until I pull over and shut it off. Had it to mechanic and he replaced the Mass Air Flow valve. Was better for awhile but now worse. O2 sensors maybe? Need advice please.

I would begin by checking the car with a OBD scanner. Good $40 tool to have with a 15 yr old car. The LHM could just be a product of the engine issues or you could have a transmission problem too. Might as well start with the cheap stuff.

FYI - If you get a lot of stored/pending codes, clear them all and then drive for a couple of days before rescanning. What returns will be the relevant trouble codes.

If you acceleration with wide open throttle and you get good respond no hesitation, driving with engine rpm around 2500 and slowly acceleration and engine hesitate and idle steady but maybe a little high then it is a good possibility your problem is 02 sensor. I guess normally if if your fuel pressure or volume is off you should have problem from dead stop also.
Check fuel pressure first anyway and fuel volume.