89 Dakota -- runs like crap overnight

Hi,
I inherited my mom's 89 Dodge Dakota V6 with TBI. It hasn't been maintained too well for a while, but neither has it been driven much. It drove fine for about a month after I got it, being driven
occasionally. It did have an issue with very occasionally dying immediately after starting. On the second start, it was always fine. I figured it would go away with the tuneup I would give it soon. Then one day when I went to drive it after it had sat for two days, it would barely start, once started would bog badly, and die unless revved. When it was driven, it would hesitate badly and then lurch forward, or die as soon as it was in gear. The engine smelled rich. The engine only smoothed out, a bit, at high RPMs (3000).
No codes in the computer. I replaced the air filter, plugs (quite worn), cap, rotor, wires, coil. It ran less bad. I then replaced the MAP sensor, since it seems to be a common issue, and also cleaned the sensor contacts and the contacts in the computer on the fender. That made no difference. It will start, no longer dies immediately, and will idle rough. Still hesitates badly, and occasionally die in gear. The power kicks in suddenly at a 1500 - 2000 RPM, and the truck lurches.
I'm next replacing the fuel filter, which is likely ten years old or more. I plan to do the rest of the basics for maintenance to get it to a good baseline. However, this happened overnight, indicating to me that something failed overnight. I'm also going to pull the O2 sensor to see if possibly the catalyst collapsed/clogged. Any other suggestions for possible culprits?
Thanks.
Larry
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IAC valve. just went through something similar. AutoZone carries them.

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Abby Normal wrote:

Thanks. However, did you have issues at RPMs above idle, and hesitation/lurching? Unless this Dodge is different from other cars I've worked on, the IAC is just a bypass valve to control idle when the throttle is closed. My cheapo Haynes manual doesn't have a air flow diagram. I believe that at open throttle, it should make no difference. This engine runs rough at idle, and open throttle. It runs better at higher RPMs, but still quite rough.
Larry
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After some of the "good" advice you received, I would suggest to test the EGR back pressure valve, That is the valve that sits on the intake man. close to the throttle body, it has two vacuum lines on it. OK now that we know what it looks like, let's check it. Remove valve from the EGR valve, with a small screwdriver gently pry the valve open (just as if you are looking for pearls in shellfish) inside you'll see a diaphragm, gently inspect it, if it is cracked or split, well, that's the problem. Replace the EGR valve assy.
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wrote:

Naw, it's a blown hub cap gasket.
beekeep
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Either that or it needs muffler bearings!
DJ

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