Idling rough

Take a look at the throttle body boots. The last 9 I looked at had cracked boots, and unmetered air into the system can cause some issues (lean). You can try the old spray starting fluid around anything that may be leaking air while the engine is running trick, if RPM changes when you spray, for example, the throttle body boots then you can expect them to be leaking. Same goes for cylinder base gaskets, crank seals.

I'd also look at the TPS calibration.

Others will chime in with more educated guesses than me. These are just the two thoughts that popped into my head.

The following have all caused idle issues for me in the past....

TPS calibration
TPS pigtail
fuel issues (in my case I had a leak in one of the injector lines)
bad connection in the electrical wire connection to the coils (not the plugs themselves but rather on the other side of the coil itself)
stator wires cut due to separation of flywheel innersheath
bad pto seal (broken belt took it out...idle wasn't eratic though...just constantly high)

Crank seals
Throttle body boots/vacuum leak
Bad aftermarket reeds
T.P.S.
Rob