'91 200TQ - hard starting (still)

[Bart Oleksy]

This has been an ongoing problem for quite a while now, where the car 
will start like a shot if you just turned it off, but the longer it 
sits, the longer it takes to start.  It turns over just fine, but take a 
while to 'catch', and will stall if I don't keep giving it gas.  After 
about a minute, it's completely fine and drives nicely.

The fuel pump check-valve has been replaced and I've even had the 
(noisy) old fuel pump replaced with a new one.

What other things should be checked as possible culprits?  One mechanic 
had me trying a 'better quality' of gasoline (from Petro-Canada vs. 
Husky or the grocery store stations) but there's been no difference 
since I switched over 2 months ago either.  another suggestion was 
something to do with the injectors, and a different mechanic thought the 
spark plug gaps should be checked, although I expect that won't be the 
problem somehow.

I'd appreciate any ideas you people might have on this for the next time 
I bring it in...thanks!

Bart
'91 200TQ
'86 CGT