'95 3.1 running rough when cold

'95 GA 3100, 135k miles.

this is my gf's car... no service history to speak of.

few weeks ago car sat all weekend in the cold, and upon trying to start, it wouldn't. took about 5 min of cranking and spit/sputtering until it finally unwillingly started. flooring the car was more productive than not flooring it while cranking. ran messy for a minute or so, then smoothed out.

couple days later, started hard again after sitting all night. GF says black smoke puffed out when it fired up.

suspected maybe a gummed/leaking injector so ran bottle of cleaner through a tank.

car has not been hard starting to that degree since, however, in the first 2-3 minutes of operating (engine cold) it has a rough idle with noticeable missing/chugging at idle and low speeds. once engine warm, everything seems fine.

i'm replacing the plugs tonite, hopefully that will either fix the problem or rule out plugs (i'm hoping to find them fouled as that will rule out ignition hopefully).

any other ideas?

Sound lik its getting flooded and fauling out the plugs. With the build up of fuel while cranking, then when it fires up all that fuels burned and spews out that black smoke.

Plugs and or new wires should help it start better. But it wouldnt hurt to try some Lucas fuel injector cleaner. Injection cars are prone to faul out in the cold, essecially if moistures present in the fuel.

plan of attack is run new plugs, wires, and another bottle of cleaner through the next tank. after that run some isopropyl through and rule out water in gas.

take it easy on the cleaners. You can use to much and it may be harmfull to the fuel system. Most cleaners are good for 25gallons of gas. And to many chemicals can faul out your new plugs. Hope this helps you out cybermob2 .

update...

replaced plugs and wires... what a PITA on those back 3.

ran perfect after replacement... one of the front 3 cyl plugs was fouled really bad, all had some fouling but not to that degree by any means. bad corrosion on a few of the coil posts, cleaned and greased.

i'm suspecting a sticky/leaking injector on the fouled cylinder. none of the other plugs were fouled nearly as bad.

i need to look around and figure out options for injector service/replacement if the problem reoccurs with the same plug fouling. (i have heard horrors of DIY injectors turning out costing $$$).