'88 Ranger - 2.9FI 5 spd 2X4 lotsa miles on it (over 212k). My problem is this. this thing runs great, fires up first try every time, idles good and runs smooth, never have any trouble UNTIL I drive it for approx. an hour to an hour and a half, could take longer but usually not much less. (tends to vary more depending on the air temp) What happens if I can explain it right is that it will all of the sudden just start running like I have a tank full of water and a carb. It sputters real bad and doesn't pull well unless you hammer the throttle then it will go unless you let up then it's back to stuttering. If you let it idle at a lite it will idle when you first push the clutch in then kinda drop until it almost stalls. If you are just cruising along it just kinda draaaaags down until you give it some gas. Now the part that's making it tough to figure out, if I go out tomorrow morning it will be like it never happened. I changed the control module on the distributor because it seems like a heat problem, it made no difference at all. I put a tester on when I got home tonite and the only code I got was the mass air sensor out of limit. I have had them go bad on other vehicles and never had problems like this so I don't think that is causing the primary problem (mite be contributing). Everything seems to point to a heat/electronic problem to me. ANY IDEAS?? Anything would be helpful. Normally I wouldn't let it bother me cause it's just my run around (read cheap) but my step-daughter is about an hour and 15 min from here which is right on the edge of it's acting up, if I drive down and back it will definitely go kerflewy before I get home so I'd really like to get it fixed without spending an inordinate amount of money on it.
BTW - It always makes it home I just got to pound the daylights out of the throttle to get it here.
Also it doesn't act like the TPS, there aren't specific dead spots in the peddle, tho I think that may be the next thing I change.
No water in the oil or vice versa and it doesn't burn any oil, no bubbles in the water either.

 

Fix the MAS if a code popped, reset the system, and drive it again.

Once you go see your step-daughter again, see if it happens, if it does pull codes again and tell us.

 

Won't be drivin back down there any time soon. It has always made it back so far but I won't count on it doing it again and if it quits on the turnpike the tow would be more than the truck is worth. So off to the junkyard it would be.
I'll change the MAS and see what it does but I know it isn't the problem because it just runs too good most of the time. I've never had a MAS bad where the vehicle didn't run bad all the time. I think I'll change the TPS too just to make sure that's not causing any problems. The only other possibilties I can think of are the coil and the computer (I assume it has one).
If I spend too much on it I don't think I can justify keeping it to the wife as I'm not sure it will pass inspection again, it's pretty rough, but it just runs so damn good and all those miles are pretty impressive on a motor that's never been touched.
Ah well, we'll see what happens.

 

Welcome to FTE!!!

Your truck has a MAP, what was the code?

 

Wrong initials. sorry. It was code # 66 Mass Air Flow sensor or Vane Air Flow sensor- voltage too low.

 

66 is not a valid code for an 88 2.9L, try pulling them again.