Lincoln/Mercury Repair: 1999 navigator falls on face when accellerating ,, torque converter, happy thanksgiving

Question
mr. dinger, this navigator has been scanned with no dtcs set.maf has been replaced with a new one fuel pressure is 35psi to 45psi no missfires when accellerating slowly the engine runs right up to 4500, but if quickly floor boarded it bogs down as soon as the rpm starts to rise above idle, any ideas or thoughts would be greatly appreciated, thanks in advance, roger

Answer
Hi Roger and Happy Thanksgiving!

Where to start? These 333 CID engines are really awesome and I have had no trouble with the 2 I have owned. Driving both to over 100,000 miles. Fuel pressure is good but it could be starving for fuel when you jump on it. I would check the fuel filter first. Each spark plug has it's own coil, so it if was that it would misfire and drive chunky. So I don't feel it is a spark issue. I think you have a fuel delivery problem, though idle pressure is excellent demand pressure could be falling off and if the fuel pump was weak, it still would hold at idle, but might not be keeping up with demand. If the fuel filter is ok, look at the fuel pump next. One other thing to consider is the torque converter. If it is coming on at low RPMs then it would hamper performance.