[s-cars] running rough

[Nicholas]

so i'm new to this list, new to audi and new to urs4 (came from a mk5
GTI). in march i bough a 92 urs4 that's been rs2ed. coil packs appear
to be from apikol (i'm assuming 1.8t coil packs...?).

car has been running real smooth (perhaps a bit rough and boggy when
cold and consuming more oil than i expected... but smooth). tonight i
took it out and it was acting normal with the usual boggyness after
startup but when i stopped at the first light i could feel a
difference in the idle: it wasn't smooth anymore and was closer to 800
RPM than 900+. under load, at lower rpms the engine feels way out of
balance but around 3krpm the engine seems to smooth out and feels
almost normal... but i don't feel like all the power is there or
anywhere above 3kRPM. my guess is that i'm running on 4 cylinders.

can anyone help me with diagnostics on my coil packs? should i just
start with replacing all the plugs? what are some some good diagnostic
tools to have for this engine? other guess/suggestions?

thanks in advance,
-nick