1989 Voyager problem

I just got through rebuilding my wife's 1989 Plymouth Voyager 3.0 L engine plus any thing else I would find when I had the engine out like the rack and pinion and control arm bushings. The problem I am having
is one that it had before I tore into it so I it isn't anything that I did wrong. My basic reason for the rebuild was to take care of all the leaks which included a blown head gasket. Ok the problem is the engine isn't running good at idle. The first part I replaced was the air idle control valve (motor). At the price of sensors and valves I hate to just replace them if I an not sure they are defective. The air idle control valve did seem to make some difference but still if I come up to a stop light with the air on the engine will die. The van has 140,000 miles on it and still has the original fuel pump but I was told if it is bad there would be more of a high speed problem the idle problem.
Any suggestions ?
Thanks Ron in Phx
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vacuum hose off somewhere ?
MAP sensor hose, for starters...............

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No MAP on this vehicle. I have checked and tripled checked all hoses and if there is a leak someplace I sure have missed it. It acts like dirt would do in the fuel line of a carb. version. I did replace the fuel filter a few months back. It will run great for a while then go into a rough idle state then back ot running great again. I am sure a bad or vacuum hose off what not do this.
Thanks anyway and I will take a forth look at the hoses.
Ron
TranSurgeon wrote:

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Ron my 96 was running rough at idle and I'd checked all else I could including fuel pressure. I ended up having the injectors cleaned at http://cruzinperformance.com/ which did an excellent job about a year ago. Much improved. Had about 140k miles. am at 149 now.
also the 89 3.0 definitely has a MAP sensor. it is on the right fender but a problem with it will show in a check engine light coming on. good luck

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First I stand corrected I was mistaken there was a MAP which I found but have not determined if I need to replaced yet. Today I brought the van to a friends shop and he tried to convince me that the timing belt was off one tooth on the crank. I torn it down enough to convince myself that it was not off. He stated that the idle vacuum at 15 pounds was to low and that it needed to be around 20 pounds and that the timing belt being off one tooth would do that. If it was consistently running rough I might buy into it but it has a very unpredictable roughness to it. I adjusted the timing and took it for a short drive this evening and it wasn't running to bad until I turned back into the driveway and then it started to run real rough with the check engine light coming on and off as the speed went low which relates too low vacuum which at a slow idle I would expect.
I have checked and replace all the vacuum hoses that I though even looked like they might be a problem and so far have not seen any improvement. I also sucked on the end of the hoses and have not found any that would not create a vacuum. I am now wondering if there is something going on with or around the fuel pump that might be causing it. I kind of believe that fuel pump problems were hight speed related but maybe not.
I did a test of pulling off spark plug wires one at a time and it almost seems like number one cylinder isn't contributing much. All the others slow down the engine until I replace the spark plug wire but number one doesn't seem to do much. Could this be an injector problem or a valve problem from a valve not seating good enough? I have ruled out the spark plug which I have changed out without any improvement.
Answers ?? Thanks, Ron
bobQ wrote:

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