ok i got an 88 f150 4x4 with the inline 6 in it, problem im havin is it likes to idle at about 1700-2000k rpms after ive drove it as much as 10 ft. Whats throwing me off is that when i start it it will idle high for a min and then drop down to about 1k rpms and stay there all day long untill i drive the truck. Ive tried cleaning the IAC but that didnt help and im currently getting 11 mpg which is slightly frustrating.... any help would be much appreciated thanks.

 

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