88 Grand Marquis - Does this sound like a vacuum leak?

Hello,
I have an '88 Grand Marquis 5.0L V8 with about 102,000 miles, which is having a variety of (small) performance issues that I suspect are the
result of a vacuum leak somewhere. Unfortunately, these problems are intermittent, and I can never seem to reproduce them when anybody who really knows his or her way around cars is nearby. I was hoping somebody here would be able to give me their own opinion on the likely cause of these problems:
1. Engine surges at low speed. When I put my foot very gently on the gas to accelerate the car from rest, the engine will accelerate normally for about two thirds of a second, hesitate for approximately the same amount of time, then surge briefly and subsequently resume normal acceleration. (If I bring the car out of rest with a greater amount of gas, this behavior cannot be discerned.)
2. Occasional stumbling at highway speeds and less frequent stumbling while accelerating around 35 MPH or so.
3. Air vented through the windshield defrosters. When I turn off the car after a couple miles' worth of driving on a cool day, warm air from the windshield defrosters causes the windshield to fog up on the inside, just above the vents. Could this possibly be related? The really weird thing is that the windshield never seems to fog up while I'm driving the car, but only once I've stopped it after a drive.
Any guesses at the likelihood of these three symptoms being related? Does a vacuum hose leak sound like the most logical thing to check for first? Thanks in advance!
Mark
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| Mark Shroyer < snipped-for-privacy@mail.portland.co.uk> |
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My opinion is that you have several small problems. The first thing to do is any due or overdue maintenance. Replace the plugs, wires, cap, rotor, air and fuel filters if they're due. I think you have 3 problems. 1. Ignition weakness, 2. Dirty intake system or nasty injectors, 3. A partially stopped up condensate drain in the air plenum. It won't hurt to check the vacuum lines tho.
CJ
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The fog on the windshield is normal if the rest of the heater functions are OK. It should go away quickly when you restart the car.
As the other answer says, do the tune-up thing. I ran into similar symptoms on my parents '88 and a big can of Techron injector cleaner cured it.
PoD
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