gear2only is a better algorithm to use for both tran and pss. Euler introduces more numerical damping.
When you say "very tight" max step, what do you mean ? I would use a max step of no less than say 100 points of the oscillation freq... (often i would use only 50) .... going overboard with harmonics and too tight with tolerances might not be too clever (as it will slow you down/increas simulation time, and the models you are by no means exact, so will be working very hard to solve very very accurately non-exactly modelled devices.)

Also when you say "Upon carrying out Tran and PSS analysis, I get a mismatch in terms of fundamental frequency...", how are you determining fundamental frequency in each case, and what magnitude is the error ?
If you use tstab correctly with the same algorthm as used in tran then you do not expect any discernible differnce. For the tran i guess you are setting you dft correctly and fairly so that you would expect the same result in the first place?

So you are looking at the time waveform when doing the transient run and measuring the frequency with cursors after a certain amount of time where you think the ocsillation has sufficently settled (ie the tstab time you will use in the pss). I assume also you are expecting ~2Ghz on one output and  ~666MHz on another output.

Lets say you setup a max step of 10ps and use gear2only for both tran and pss runs (including tstab period). To make the simulations a bit quicker, let say you use errpreset moderate, and switch off high order (only really needed when looking at small signals close to what would otherwise be the numerical noise floor).

Now on the pss run, I guess you are ploting/printing the pss fundamental frequency.... i have a couple of questions you might ask yourself to help solve this issue:
1) are you saving the initial transient to learn why you get the sudden unexpected jump in pss fundamental frequency ?
2) have you plotted the pss outputs voltage against time (using the main form) to see what the steady state waveform against time looks like on your 2 outputs ? This should closely match your transient simulation waveforms.
3) is your initial guess at the pss fundamental something close to 666MHz ?
4) you will only get a good idea of the amplitude at any given frequency by doing dft on transient waveform, or plotting "sprectrum" on the pss output form.

Anyway hope these points help you resolve you issue.

cheers

aw

Sounds very strange... maxstep of 1ps is a bit over the top. as i said 10ps should be easily small enough for good accuarcy...
So you are no longer getting the frequency wrong now, just the amplitude ??
Are you sure you are not confusing single ended output against differential or peak against peak2peak ?

If you are looking at both time waveforms of pss and tran after the same amount of time (ie after tstab for tran) and the waveforms are drastically different then I think your particular case needs addressing be Cadence themselves, who given the netlist, setup etc. can comment more appropriately for your exact situation.