part-throttle shudder

[ckrug at indy.rr.com]

My '89 200Q has recently started showing an odd behavior. At partial throttle, I have an intermittent shudder or shaking felt from the engine, usually for no more than a second or two, then it's fine for a few seconds before it repeats.  Below .3 bar, it isn't noticeable, and above .6 it smooths out also, but at .5 bar of boost, it's not good at all.  I'm thinking it's an ignition issue, as I'd had a bad plug wire recently that caused a similar miss.  At the time, i didn't replace the whole set, as I had a spare #5 wire around, but I did change the cap & rotor and checked the plugs, which are the correct ones, W8DTC if I remember.   Is there anything else i should look at? The only other issues i have noticed is unusually long cranking time before it starts, and the water temp light always comes on after about 10 minutes on the road, regardless of actual temperature.  I know it needs a new multi (mal)function temp sensor.  I'll try to pull codes on it in the next day or two, but I know there are some things the codes don't tell me, so I thought I'd ask the list as well.



Calvin