Thought it was fixed...help please

[golefty]

I have a 70 911E Targa, with stock MFI, etc...
I was having a problem with my idle/RPM after I engaged the clutch... RPM's would go all the way down to "O" for a second than rise to 1100 and I had significant power loss in general. It appeared to be a fuel system related problem, so I put a can of "Sea Foam" into the gas tank and the problem ceased after around 50 miles - so it seems to have been a clogged up fuel injector problem.
But I now have a new problem...
I am getting a somewhat rough accelration at low RPMs and if I'm idling and in nuetral and I press on the gas - the RPMs go up and then stay at around 1900 - and even if a "punch it" beyond 1900 the RPM's go up but then go back down only as low as 1900. The only way I can get the RPM's all the way down to 1100 is to turn off the car and re-start it.

Any thoughts?

I have had the fuel tank cleaned out, though not boiled - a project which I'll undertake this winter.

Thanks for your thoughts...

golefty