When you do have the problem, is it present regardless of being in park or drive?

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

When the problem occurred, it was most noticeable in P or N, however it does occur in D. The only difference is that in D the engine RPM is not able to fluctuate much due to the load on it. I believe your problem may be the same - it is being masked when in D. Think about it - putting the tranny in D does nothing electrical or electronic; it only puts a load on the engine and likely dampens any RPM fluctuation which gives the appearance that the problem only occurs in P or N.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Pull the vac lne off the fuel pressure regulator and see if any gas is evident coming from that port while running. Also check for good vacuum at the line you took off.

Hmmm... mine seems slightly different. I don't notice anything when it's in drive, not even the slightest indication that the engine would like to surge despite the fact that it is loaded.

I'll just assume that I am not noticing it for the time being, this is most likely the same issue.

AD thanks for the fuel pressure regulator tip, I don't have that on my list.

__________________
1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?