Contour Enthusiasts Group Archives Forums General Troubleshooting Backfires when cold

95 Contour 2.5 automatic, 59K miles.

Start it up in the morning, idle jumps to about 2K, then down to aabout 500 and almost dies. Floorboard it and it backfires. Milk it easy, drive it a half mile and it's warmed up enough it runs perfect like a striped ape--go figure????

I have done the following:

Replaced IAC
Replaced Fuel Filter
Cleaned MAF sensor
Replaced Air Filter
Used injector cleaner
Used water dispersent in fuel tank
Checked for vaccum leak--none found

I can safely say it's not the plugs/wires--it would be doing it ALL the time not just upon coldstart & 1/2 mile of driving (doesn't matter wheather it's winter or summer).

Any Suggestions on what to check next?

hi, try replacing the upper and lower intake plenum gaskets, on these 2.5 engines, gaskets usually start to go bad at about 50 k miles, only at start up and cold (usually overnight), then runs fine after engine warms up

Plenum gaskets--like intake manifold gaskets?

Also--absolutely zero CELs (have not checked for any codes).

Mine is doing the exact same thing. Intake plenum gaskets? How bad of a job is this?

Plug and wires. It doesn't always have problem if they're bad. I had that problem before, changed the plugs/wires and it was gone.