cis sputters
 

before 3500 rpm it sputters then it just breaks through and runs fine. It gets worse at normal opp temp

Change the plugs.

That and check your fuel fillter.

I would suggest removing your spark plugs, look at them carefully, and see if one is darker than the rest. Under normal circumstances (otherwise properly maintained and tuned car) your symptom sounds suspiciously like a bad injector. A dark plug will tell you which one. If your plugs are all burning about the same color, then you might have a fuel distributor problem.

year of the car could be helpful.

check plugs, wires, cap and rotor first.
then check the timing and make sure the advance is working properly, then move on to the CIS.

how is steady speed driving below 3500?

if you have gages, go ahead and check control pressures.

what about idle?

if you blip the throttle at idle, do the RPM's settle down OK? IE, do the RPM's drop below idel then come back up?

all what was said before and... air leaks ?

All that's said before & check for H2o in the tank :(