I'VE GOT AN '87 CAPRICE 305/350 SETUP AND THE CAR SEEMS TO RUN FINE AT TIMES BUT THEN DIES.ALSO ACCELARATION BRINGS UPON THE SOUND OF A EXHAUST LEAK FROM THE PASSENGER REAR SIDE OF THE ENGINE.I'VE BEEN BUYING NEW PARTS LIKE CRAZY TO NO JUSTICE.LIST INCLUDES FUEL PUMP/FILTER, AIR FILTER, SPARK PLUGS/WIRES, IGNITION COIL, AND REMANUFACTURED CARB.STILL THE CAR RIDES GOOD SOMETIMES AND DIES OUT OF THE BLUE.COULD SOMEONE HELP ME WITH THIS HEADACHE OF A PROBLEM?  

could be the efe assy in the exhaust system ..

whats an efe... early fuel evaporation system..

it is a vacuum operated trap door in the exhaust manifold that when the engine is cold it closes and redirects exhaust from one side up through the crossover under the carb to heat the carb to make it run better sooner... the vacuum hoses to these go bad. when vacuum is lost to this valves actuator it closes...

vacuum rounting looks like it comes from the front base of the carb where the pcv hose tees off in two directions goes over to it's own vacuum thermal valve and the smog pump diverter valve.. from its own vacuum thermal valve it goes directly to the efe actuator on the passenger side exhaust manifold bracket...  az has a vacuum diagram on their repair info website under 86 elcamino 5.0


pm me if you cannot find it.  i will send a  direct link.


also do you have a scan tool.???? or a dwell meter..::::????

if you have a scan tool  you can watch the mix solenoid duty cycle.. it should vary between 28 to 35 at idle..

you can also look at this same measurement with a dwell meter hooked to the green connector that is near the carb and not hooked to anything. 6 cylinder scale..  if it sticks beyond 10 or 50 you have more trouble.. and there are trouble shooting charts to figure this out...

and .,...  did you install the ground strap under the coil that hooks to the center terminal on the hei wire..  wait.. thats got a small cap...    got a timing light???

hook it up .. tape the light trigger on.. and the light to the windshield.. drive the car..   when it cuts out watch the light..  if it is still flashing when the engine dies.. it is fuel related or exhaust...  it the light goes out at the instant the motor dies.. it is ignition related..  

I have an 87 caprice wagon, its got the 307 Olds not the 305 Chevy, but i swear by changing ALL the vacuum hoses at least once a year. It runs so much better after I change them.  Also check the vacuum canisters to. I couldn't get the wagon running for almost 2 weeks once with similar symptoms to yours. I changed all the hoses with no luck and unintentionally found a crack on the underside of the vacuum canister that was out of sight.  Put in a new canister and it  runs Great now.  

You may also want to check the p.c.v valve if it has the plastic 90 degree elbow it could have a hair line crack in it.  

Also check for a loose wire on the alternator. The one that charges the battery and provides power to the car. If it's loose it will cause the car to stall.