Windstar 3.8 Chugging/Missing

[CraigRK]

Here’s the story . . . ANY help appreciated. 1998 Windstar 3.8L ~300,000 km

For quite some time (months) I noticed a slight chugging at low RPM’s. This was slowly getting worse over time, but curiously, would instantly clear up when the engine revs hit 2000. Seemed like a misfire at low revs?

Then, the chugging got much worse, and over the course of a few days spread through the RPM range. The vehicle became virtually undriveable, with the engine chugging and missing. The CEL comes on and flashes.

I tried unplugging the O2 sensors – no difference. At Advance Auto, the guy checked the codes and got O2 sensors codes (they were disconnected at the time) and missing on cyl; 1, 2 and 6. (Duh!) He said those were the only codes.

Although the plugs were fairly new double platinums, I changed all six plugs. Then the coil pack ($85!!!). Then the plug wires. Then the air filter. It seems to have improved slightly, but is still chugging and missing. I have NOT gotten to the root of the problem.

I have a very limited budget, and can’t afford to keep swapping expensive parts. I was wondering about the crankshaft position sensor, the crankshaft angle sensor, I’ve read here about the camshaft sensor(???) and is there a way to test the MAF without replacing it? (I can’t return the new coil pack or sensors once installed.)

Again, any thoughts or insights would be appreciated.

CraigK