A bad vacuum line was my original thought, thanks to these forums, but I couldn't find a leak anywhere.

My Ranger is at a local mechanic right now. I will post the results when I have them.

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2000 Ranger XLT, reg. cab, flare-side
2.5L gas, 2wd, automatic, A/C
200k
Iowa

The mechanic is still trying to figure out what is wrong. He has tried new coils which didn't solve it, luckily he was able to return them.

He says the compression is good, which should mean the head gasket is ok.

The fuel injector seems to be ok, too. He did replace the timing belt, which needed done badly anyway.

I am going to give him a couple more days and then I guess I'll have to take it to a dealership.

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2000 Ranger XLT, reg. cab, flare-side
2.5L gas, 2wd, automatic, A/C
200k
Iowa

The IACV is probably bad after 200k miles

The IACV is probably bad. $43 and 10 minutes to change

Well, I disconnected the IACV and the engine idle went very low and rough to the point of almost dying, so I figured it was functional.

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2000 Ranger XLT, reg. cab, flare-side
2.5L gas, 2wd, automatic, A/C
200k
Iowa