[LILBLU91]

91 Escort GT, car had been sitting for 6 years. Basically stock, header, cold air intake, cat converter, sport muffler.
Car failed PA emission test ( running way rich ). Performed general tune-up plugs, rotor, wires, cap. Dealer did the fuel system cleaning and changed the fuel filter. It all helped but not enough to pass emissions.
Since the car wouldn't warm up we changed the thermostat and oxygen sensor. Now the car seems to be running lean, stutters when throttle is blipped after warming up for a few minutes and missing until around 2000-on up while driving then smoothes out.
I was hoping the computer would adjust and tune itself but after driving for a few days (10 mile trips) it isn't getting any better or worse.
I'm old school mechanics MG's, Austin Healey's so I need a good automotive computer manual. I have a Haynes manual for general repairs and looking to this web site for directions.

updates:
-while testing o2 sensor voltage was suggesting engine running lean so changed o2 sensor again... no noticable improvement
-attempted to check timing, marks not existent, so we winged it till the car ran decent...(timing fully advanced)
-so now the car only misses at idle
-checked for engine codes and there doesnt appear to be any

 

[agrowagon]

have you changed the coolant temp switch not the one for the gauge{1wire} but the other one that is {2 wire i believe}
another possibility could be a vaccum leak check the intake connections

one thing that you can check is the VICS solenoid i broke mine working on the car and didn't know it. the car ran like crap kinda the same symptoms you are having. i advanced my timing and it helped but there was still a problem i JB welded it to get me buy till i got a new one thanks to LOWETGT check if the vaccum lines are connected to it and not broken. if that is the problem then retime your car to the stock timing marks and adv. or ret. as needed

here is a picture of the solenoid that i reapaired

 

[defiler]

Might be a longshot, but take some brake parts cleaner and spray around the engine bay... if there's a vacuum leak you'll find it quick. When a car sits those vacuum lines start to rot quick, and even a small crack can cause a bad idle symptom...

 

[agrowagon]

Might be a longshot, but take some brake parts cleaner and spray around the engine bay... if there's a vacuum leak you'll find it quick. When a car sits those vacuum lines start to rot quick, and even a small crack can cause a bad idle symptom...

1+

 

[Escort92Man]

my vics control solenoid did the same thing :S I hit up the junkyard and got one, it was 1.50 lol. I might be able to get one and put in an padded envelope and send it for a few postage stamps, but if Lowetgt has one for you he'll get it to ya!

yeah even the smallest vacuum leaks make an engine run like poop, it stinks but it's a fact, just trace all the vacuum lines and poke and prod around carefully, make sure all your cold air intake clamps are good and tight etc, good luck finding out what it is!

 

[LILBLU91]

missing at idle

Thanks for the tips. We replaced the 2-wire tempature sensor. It seemed to help some but not enough to put the timing back.
We just found that we have a heater hose leak so I think I'm just going to replace the vacuum lines while in there as well as all the hoses.

 

[LILBLU91]

Easier said than done, replacing all coolant and vacuum line