Hesitation/cutting out at speed when engine is warm .. help!

I have a 93 Mercury villager. (Aka Nissan Quest). I've had the van a short time, and pumped some cash into a new timing belt, etc. She starts, and seems to run fine. But today, when coming back from getting new tires. She
seemed to be starved for gas. Around 35-50 miles an hour. You can press on the accelerator, and she'll hesitate, almost like she's going to cut out. If you floor the gas peddle, she kicks down a gear, and seems for a bit. Turning off overdrive seems to help a little, but when you get to a certain speed, she starts to act up again. She's had a full tune up (plugs, wires, cap rotor, fuel/air filter, pcv valve, timing belt/water pump). I've checked the transmission fluid, and it's not low.Mind you, this doesn't seem to happen until she's all nice and warm. What type of things should I start looking at? Any insight would be GREATLY appreciated.
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clevere wrote:

Bosch platinums? Could be the start of a MAS dieing, ussually caused by the use of cheap air filters..
--

Steve

http://www.atlantaracing.com
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I had a fuel injected vehicle (TBI) that did the same thing. What I found was a break in the rubber fuel line that connected the fuel pump output (inside tank) to the tank header inside and on top. This dropped the fuel pressure enough to allow the fuel to boil inside the steel fuel line routed closely to and all around the engine when accelerating while the line and motor were at operating temp. Maybe you have a fuel delivery problem?
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Could have cracked a plug putting it in. They are usually fine while fitted it's only putting in and taking them out that puts cracks in them.
Don't bother with anything other than NGK plugs.
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Could be that your coil is beginning to break down, if it is always at the same revs, then it is most likely an electrical prob. If it is always under the same load, it is most likely a fuel prob. It is a rule of thumb but not a defining rule, cars do some weird things and can be real headaches. Just go through the basics until you find the problem. Fuel Air Spark. Checking for codes is not a bad idea either.
Scott.
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