Q: I have a 1993 Plymouth Sundance with a 2.2-liter, four-cylinder engine. I have had a new catalytic converter and a new exhaust system installed. Last year I had a complete tune-up with a new fuel filter. The problem is that when I accelerate from a complete stop, the vehicle does not want to go. When I go up a steep hill it climbs slowly. The acceleration from a complete stop is so bad that I am afraid that I am going to get hit from behind. I have put a bottle of STP dry gas in for the second time, and it has started to get better. I had the engine checked, and it is fine. I had the transmission checked, and it is fine.

My car was not used for two months because of a surgery that I had, and I wondered whether this had anything to do with the problem. It didn’t do this before it sat. - Donna Passarelli, Greensburg, Pa.

A: Donna, there can be many reasons for a loss of power. First a question: Does the engine run smoothly or does it run roughly and shake as the power loss occurs? If it runs smoothly, we can assume the engine’s cylinders are contributing equally, albeit poorly. Roughness and shaking indicates one or more cylinders are misfiring.

Your comments about the vehicle being parked for a while and partial success with the fuel additive tempt me to explore fuel contamination before the other possibilities. Could the Sundance have had a loose or missing gas cap during rainy weather? It’s also possible you inadvertently purchased a few gallons of water along with a tank full of fuel. Water in the fuel tank can cause a variety of problems as it can restrict the flow of fuel through the fuel filter and causes corrosion of expensive fuel-system components.

Checking for fuel contamination is easy, once a sample of fuel is obtained from a separated line or service port. Within a few moments, water and other contaminates will settle to the bottom of the test container, with the water resembling blobs of off-color material. If more than a few drops of water are detected, it’s best to remove/drain the fuel tank and inspect the inside for signs of corrosion.

Once it is refilled with fresh gas and a new fuel filter is installed, you should be in good shape. If only a small amount of water is indicated, I’d renew the fuel filter and try a larger dose of dry gas (ethanol), which absorbs water, helping it to pass through your fuel system.

Other causes of a substantial, yet smooth, power loss are: a lack of fuel pressure/volume - often caused by a faulty fuel pump or dirty filter; a restricted exhaust system; an air cleaner obstruction - perhaps a rodent nest; incorrect spark advance - a mechanical fault on older engines or an electronic problem on newer ones; or a transmission fault - it’s not providing the correct gear or the torque converter clutch is applying inappropriately.

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