M70 engine runs rough acceleration only-stumped

[bshupe]

My 1990 750iL (about 70K miles, nice condition car) started running rough about 6 months ago. It would start and idle fine, but accelerating from about 2000 rpm it would miss and shake a bit. I replaced the plugs. It ran better for a few weeks and then the miss/shake came back. So I replaced the plug wires (and reset computer codes per Shogun) and again it ran OK (not like new) for another few weeks and the shake and loss of power comes back. So I replaced the O2 sensors and reset the codes again and it has been stellar for 6 weeks, great accaleration - fixed, no. Yesterday coming back from a 70 mile trip from home it started up again to the point were I barely got home. No power and extreme vibration during acceleration only. Starting, idling, low demand on engine its fine. How can a car be fixed and go back to its old ways on its own? No engine or EML light on. Any ideas? Thanks.

[Highline]

that would be the first to check. Then check for air leaks around intakes, pull the intakes by hand and spray brake cleaner into that area to see if idle changes.
And first thing I would do is cleaning the throttling valves, completely, often the brushes get stuck and then the problem starts.
See pics on my website, also under refence data there are the data to test them, and here a good write up
http://www.mwrench.com/Whitepapers/DKMotorcleanup.pdf

Is the EML light coming on for 2-3 seconds when you switch ignition on and then disappears? If not, the problem is in the cluster. See link to Johan & Sean on my website, under electronics it is shown how to repair this problem.Shogun E32 Tech Tips: http://twrite.org/shogunnew/topmenu.html

[bshupe]

[bshupe]

So many of the links seem to be dead - I'll try your site.