We had this problem with our 1988 wagon as well at 150K miles.

I replaced BOTH fuel-pumps for about $300. One was definitely not making enough pressure, and I didn't want to worry about the other one, so I replaced both.

I also changed out tank screen (the old one was clean) and fuel-filter so I KNOW everything is clean.

:-) neil
1988 360TE AMG
1993 500E