loss of power and spuddering

[Transporter42]

Hey guys, i have a situation on hand. I have a 98 Q45, and its acting crazy. sometimes at a stop light it would spudder like it was going to die out. then as i hit the gas pedal a lil to move forward it would do it again, until finally it would stop. i have a service engine soon light on, and had it read by a professional. the reader reported bad knock sensors, and a miss code. i replaced a coil that he said looked bad, but the car ran a lil smoother, then while my lady was driving it, and a million miles away from home (of course) it stated the same thing, and then their was a loss of power in the throttle at about 60 mph. she dropped it down to 40 and it wouldnt do any more than that.had to be towed home. the next day i cranked her, and she started right up and sounded fine. after a good 10 minute warm up, the problem again. called around and asked questions, got a lot of fuel pump answers. ive owned her for three years and no issues, does anyone here thinks it could be pump related, or am i in for a new vehicle...... how do you tell if the ignition coils are bad, why only when it heats up does it act weird.. can anyone help with this inigma?

[loystock]

Most likely the housing of your knock sensor is cracked hence the intermittent problem. Normal resistance of KS is 550K-ohm. Below is a link on how to replace the KS (a major job), courtesy of "paranoidjack."

zerothread?id=420801

You may also have a problem with your fuel pressure. It should be @ 38PSI with engine running and @ 45PSI with engine OFF (ignition ON). Remove and check the fuel filter (located in RH wheel well). If the filter is good, you should be able to blow air thru it with little or no resistance at all.

Ensure the fuel line is empty before removing the fuel filter - FIRE HAZARD. With the engine running, pull out the Fuel Pump fuse and let the engine die. Crank the engine a couple of time to ensure line is empty. It would be better to check the fuel pressure by connecting (T-fitting) a Fuel Pressure Gauge between the fuel filter and the fuel rail.