Chevrolet Suburban

Ok. 1991 3/4 ton 2wd chev suburban 5.7l tbi 180k miles
ran great up until a week ago.
went to start it and a loud hissing noise eminated from tbi. Also seemed to be putting in way too much gas. Idles and drives really rough when cold. Coughs and sputters and smokes until warmed up then runs fine.
I originally was told it was the coolant temp sensor so I replaced that
replaced: coolant temp sensor- no change
replaced throttle position sensor- no change
replaced map sensor- no change
replaced o2 sensor- no change

removed and cleaned vaccuum openings on tbi - no change
no vacuum leaks noticed.
throttle plates are not sticking or worn
new fuel and air filter less than 5k miles ago
allways changed oil on time if not before

once it warms up- it runs fine but a bit rich. No ses light

however! If I unplug the coolant temp sensor all the problems go away. Except I get the ses light blinding me.
all parts were replaced with new parts
cap and rotor, wires and plugs look fine and were new 9 months ago. She allways runs cool and has never overheated.
also checked connections and wires on all replaced parts and they seemed fine.

please help! This problem just SUDDENLY started (she ran like gangbusters 2 days before. I went out of town and when I came back and started my baby this all began) and im too poor for a mechanic.
im out of ideas the last thing I can think is the ecm
also replaced the spark controller in the distributer a few months back.
November 17, 2007.

Try the EGR
take it out and clean it

Nov 17, 2007.
You just about narrowed it down to the MAF or AIS same part different name. Also the IAT may be a tad bit dirty.

Nov 17, 2007.
If the maf/ais is that the bolt on plunger thet attatches (screws into) to the back of the tbi? Has a 4 prong connector?
If so allready replaced that too.

Nov 17, 2007.
It should be located near the air intake hoses, usually just look for wires going into the hoses or the air fliter housing!

Nov 18, 2007.
This morning I checked the EGR also removed and cleaned out the EGR solenoid. Put it back on and started it and it ran just fine.
Drove it around a lil bit and then put away my tools and made sure that everything was put on tightly etc.
Now it wont run again!
Now my temp gauge inside the cab dosent move.
Its just getting worse by the day.

Nov 18, 2007.
Temp gauge
just look for the sending unit wire may be off
did the egr had a lot of carbon
it want start know why did u check what missing spark fuel pulse.

Nov 18, 2007.