My 103 engine has a hard time pulling my '91 300SE around under the best of conditions.

However, lately the low-end torque seems even worse.
with 160k miles, I suspect the long timing chain may have stretched enough to retard the valve timig a bit - a sure way to lose some low-end torque.

The old motor is in great shape - valve job at 120k, good compression, no oil use, smooth idle, well-tuned, and good power above 3000 rpm. It just struggles more lately to get that big old car going from a red light.

I know these chains are not trouble-prone, but it's a pretty long distance from crank to cam sprocket, and just a bit of stretch could retard the timing 5-10 degrees I would think.

Any thoughts or experience here?

Any other ideas on what could hurt the torque below 3000 rpm?
Maybe a partially clogged cat is about all I can think of.

tks,
s-class guru