hello

i have a problem with my 94 that is puzzling me.

6speed
140k miles
no ses light
service ride control (z07 option) light is on, but that is a bad servo that
i know about
no other indicators on
new battery
alternator normal output
all other temp indicators in normal ranges

the symptoms started a few months ago. in top gear at high way speeds, it
will seem to miss when a demand is placed on the engine (going up a hill,
passing, etc). in the ensuing months, it seems to have gotten worse, in that
it now:

at idle (which used to be around 800rpm), it would start to hunt, going from
800-2000, with no throttle input. during around town driving, say in 4th at
45, the engine would speed up so the car would accelerate, with no throttle
changes being done by me. the pedal doesn't move under my foot, so it's not
a spring, i believe.

i replaced the iac valve and airfilter at this point. when the old one iac
was removed, it had a lot of crud on it. i cleaned out the opening to the
throttlebody, but didn't take it off for a complete cleaning. i also
replaced the water temp sensor, as i noticed the harness connector was
cracked.

the problem has now changed, in that the idle has dropped to an abnormal low
of 400 and seems to almost stall. it still has the missing and bucking at
constant speeds, and also misses pulling away from a stop.

i took it to my local mechanic, whom i've had for about 20 years. he noticed
that every time it surges, the service ride control light changes intensity.
he seems to feel that the computer is bad and is affecting the timing
somehow, and said i should take it to the chevy dealer.

could this be a fuel delivery problem (fuel pump, filter, bad injectors)?

are there any other sensors that this could be, or does this sound familiar,
and if so, are there tests for them so i don't have to start throwing
expensive parts at the problem?

thanks,
charlie
cave creek, az