1991 Ford F150 stuttering and rough idle

1991 FORD F-150
185,356 MILES • 6 CYL • 4WD • MANUAL
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LEWISCYPHER
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I was driving my truck and it started idling rough and stuttering under medium accelaration, if I put it to the floor it hesatates for a second then accelerates good. this problem didnt occur gradually but started suddenly. The check engine light is not comming on so I assume the emissions control sensors are working? Tried putting a set of plugs and wires in it today with no change.
Nov 16, 2008 at 5:13 PM
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JAMES W.
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Check your EGR valve to see if it is hanging open a little bit. You may have to remove it phisically to see if it is closing. Next, you can do a resistance test on the throttle position sensor, TPS with an ohmeter. With 185K on the truck, it can wear a spot on the coil and creat a "weak" spot. The ECM will usually pick this up and trip the check engine light, but sometimes it won't until the condition gets worse. Hope this helps.
Nov 16, 2008 at 7:15 PM
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LEWISCYPHER
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ok i checked the EGR valve seemed like it was closing. Just to be sure I made a gasket that covered the port to the fuel injection manifold. There is only one port so i figured that would be ok for diagnostic purposes. there was no change. I also picked up a TPS It was only 25 bucks so i bought one and to no avail still running rough at idle and hesatating on acceleration. Any more ideas?

Thanks in advance!!!
Nov 18, 2008 at 6:17 PM
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JAMES W.
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Lets check for a vacuum leak. With engine at a warm idle, take a can of regular carb cleaner and spray it along the intake where it meets the heads. also any intake ports and lines. If you hit a leak anywhere the RPMs will pick up and the motor will smoothen out for just a bit. Let me know,Jim.
Nov 18, 2008 at 11:37 PM
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