I still have some valve noise, but 'think' it got better.
Getting the timing perfect (during the timing belt change) seemed to help (compression much more uniform).
Currently on a "2x desludge" diet (1 quart of Pentosil (spell), change oil early after 2000 mls or so; repeat). Also, added some 'old engine, quiet engine' additive which reduced the the valve noise.

Hesitation, poor starting, misfires:
- I mechanically cleaned the TB hole to the EGR (was fully plugged up, solid).
- last week (also on a 1996 12V), looked into engine that was reported ("blown head gasket") to overheat, misfire. Car was definately running not on 6 cyl. Changed plugs (were a bit white for my taste), swapped ICM. No change. VAGcom did NOT show faults, but measuring values for knock where high.
- Later found crack in ignition coil pack. Ordered new and installed: perfect. No valve clutter, no codes (better than mine; this one has at least 240k miles on it, sound like a sewing machine).

==> If EGR codes present, check TB connection/hole to EGR, clean EGR.
==> IF no EGR codes, check intake air and vac lines for leaks (spray carb cleaner or starter fluid in the areas and observe if engine 'hicks up'.
==> Fuel pressure ok?
==> If not fuel or air: ignition (plugs, wires, coils).

Valve train? Can't comment if that would cause your symptoms.

 

didn't charge me for diagnosis. didnt even quote a repair price... another mechanic confirmed.. didnt want to quote price uless I allowed further diagnosis.

 

I had 'rattle can' exhaust. Cut the cats out (welded in straight pipes). Unfortunately, (different now) rattle remains, since apparently some broken cat pieces have traveled and now caught in the mufflers. Had hoped they would break down quickly, but has now lasted for 2 months, still rattling at certain RPM/load.

 

I been having the same problem.. I been looking in my owners manual and I find out that the type of gas you put in has a big affect.. If you ran your car on regular grade that is below 87-90aki it could ccause severe engine damage.Aki stands for anti knock index

 

Any news?