Dear Car Talk fans,

I have a Ford Focus ZX3 2001, manual transmission. It does not run properly. I think the correct words to use are ?it chugs?. Idles smoothly, runs smooth at a constant speed, but when I shift and start out in that gear it chugs. Not too much in 1st, 4th, 5th, but 2nd and 3rd are the worst. I am not lugging it either! I shift at 1600 to 1800 when the shift light comes on. This is low rpm shifting where you get your gas mileage. The harder I accelerate the more it chugs. When I shift at a higher rpm, 3000 rpm, it does not do it.

Unusual operation of car upon start up; doors lock and speedometer jumps up to 30 or 130. The more the speedometer jumps the more the car chugs. The way it should operate is the doors should lock after rolling some (speed sensor activated) and no jump of the speedometer.

100,000 miles on car. Took car to Chrysler dealership for thermostat housing repair and tune up, went from 28 mpg to 30 mpg on highway, Repairs; thermostat housing coolant leak, warped housing, replaced new; different mechanic ,front brakes pads and rotors, replaced new; right front strut broke (both replaced new), alternator belt replaced, battery cable replaced new, battery, starter, valve cover gasket, new plugs at 65k and 98k, battery (1st one was bad),Fuel filter replaced at 81,700, don?t know when the air filter was replaced, replaced alternator(bearing bad, whined),I took the car for this chugging problem, replaced spark plug wires ( #2 wire was melted just a little, drove around on it for 20,000 miles, no problems, mechanic said #3 was missing out also said plugs were good), replaced plugs at Ford dealership at 98k, Motor craft plugs used, Regular oil changes at 3k to 4k. Transmission oil changed twice, 60k and 80k

I have been driving around for close to 15,000 miles with this chugging problem. Does it with the a/c on or off.

My mechanic and the dealership are stumped, because there are no computer codes and no check engine light.

At our library we can access Mitchell ondemand5 and I found a technical service bulletin for tube-mounted D.P.F.R. ERG sensor, date of issue June 14, 2004, replaced with a BorgWarner part, didn?t work, still chugs. Reading some other posts I have found out that the tube can have a pin hole leak or need resoldering. Tail pipe is very very clean.

I had the battery and charging tested again, everything checked out OK.

The car is worth keeping.