Idle slows and stops after revving

[CliveElliott]

Thank you very much for your reply!!
I have a Canadian 1990 Geo Tracker, 1.6 L 8V TBI, with 3-speed auto transmission and 4WD with 143K miles (220K km). Engine was swapped about 3 years ago and has about 120K km on it.

It starts fine and idles at about 800 rpm consistently, until I speed it up to 1500 or 2000 rpm; then it won't hold the idle speed after that - gradually slows down to 500 rpm, sputters a few times and stops. (I can easily keep it going using the throttle.) Sounds like eGR sticking open to me this.

Then it won't start - just cranks, and unflood mode doesn't help (i.e. throttle pressed to floor). Is this a fuel problem (e.g. pump or filter or bad fuel?), or could the ISC be dirty?
if it dont start check spark, if sparks gone check the VR gap i the distributor, this dizzy makes its own spark and timing.
the isc will not cause sputtering but would cause idle regulation to end. if it sticks.

I should mention that it coughs occasionally when I rev it - bad gas?? (It sat for months so we added some Seafoam and 2-3 gal more gas.)
how many months, 12 ,24? 12 months


Another quirk I should mention is that the throttle doesn't seem to control the engine as accurately as I would expect - engine speed sometimes changes without my moving the throttle, and is sometime slow to respond to throttle.
correct not normal, hot idle is regulated at 800 rpm (AC off)
It does IDLE steadily at about 800 until I start playing with the throttle. What I mean is that when I move the gas peddle the engine speed doesn't respond accurately.

It has new NGK cap/rotor/spark plugs and wires, new air filter and new ECT sensor. Compression is about 130 psi (cold, WOT) on all cylinders. (We are at 3500 ft altitude so it should be 135 psi hot).
correct 139, or as you said is ok at 3500'
map hose not clogged Will look at your site to see how to check this.
, fuel filter ok? Not sure. My husband could check that; he's been too busy working on our other cars.

check engine light on , key on, then off running? yes
then use the diagnostic jumper clip and see if ECU flashes out 12s? code? for ok. yes, 12s and nothing else

if spark is not lost, usually as stall is, EGR stuck open. I see if the egr closes every time, you cut the throttle. ]I'll check your website re checking EGR. I hadn't done that yet because it looked a bit complicated for us non-mechanics.

or fuel pressure lost
or engine is flood, If it was flooded, wouldn't the "unflood mode" have an effect - causing it to at least try to fire? Unflood does nothing at all.

good luck ! thanks again!