OK if you have ever seen the movie or read the book "Christine" BY Stephen King then you will know what I am talking about. I'm still in the process of fixing the engine woes I have been having on my 240. Today I decided I would crank it up and run some fule injector cleaner through it becae It acts like it is starving for fule or one of the cylenders is not fireing. I cranked the engine expecting to hear that dreadful sputter and skip however the car Ideled As smooth as glass. I though oh good so I drove on to the gastation put some FI cleaner in it and $10 worth of mid grade at $3.05/gal this even made the all fimair clicking noise that you hear with any "true VOLVO" ,the new ones are pos Fords triung to pass them selves off as Volvos, go away. I said this is too good to be true no sooner did I get to the first stop ligh about 2 blocks away then the car started to convolse and run like well a Ford with over 30k miles on it. I said well lets see if it's just clearing it's troath and contine on I go on I 85 and headed toward oxfor about 7 miles away. All the sudden I fet that non firng cylnder kick back in. I said well lets make a round trip and see how things are going... BIG mistake the car started to act u again not waint to acclerates and misfireing and being just plane ornery. I said fine be a Bitch, excuse my mouth, and the car stalled out and would not start back. I said fine I'm sorry just get me home and tried it one more time and it started it is still running with a terible mis fire. I think I will park it unil I can look into it a littel more. It is also being weire about shifting into od/D sometimes you have to pop it until it clicks.

Start with the simple stuff like replacing the distributor cap and rotor if it hasn't been replaced in recent history. Or at least open it up and make sure there's no moisture inside, scrape the contacts clean (rotor contacts also), and make sure there are no faint carbon traces causing one contact to arch to its neighbor.
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Chris - 1990 740, 1973 1800ES (Non-running), 1993 Dodge Dakota (Still has a little paint left on it)

Definitely check out the dizzy and rotor as CM suggested.
May as well check the plugs and wires too.

If you have an ohmmeter or multitester test the resistance of your wires and wiggle them around while testing. Maybe a problem within a wire or at a wire terminal?

If it's an '89 as your sig suggests then it has a crank position sensor, aka RPM sensor.
Not a likely cause for ONE bad-firing cylinder but a known cause for intermittent ignition problems. When it gets bad enough the problems are no longer intermittent, more like steady-state.

Look for crank position sensor in the FAQ under ignition sensors. Have a look at the shielded cable going to the sensor. Wrecked cable = needs a new sensor, comes complete with cable. PITA to install, I never did one. I think it's easier if standard tranny due to more clearance?
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DAMHIK: Don't Ask Me How I Know - - - Sven: '89 245, IPD sways, electric rad. fan conversion, e-codes, 28+ mpg - auto tranny. 500 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).