'98 Blazer Possessed by Devil - Recommendations?

My 1998 Chevrolet Blazer is apparently possessed the devil, and I'm wondering if you guys might have any insights that would help me
figure this crazy thing out.

(This will be a longish message, but only because I'm trying to get all the details in.)

Here are the symptoms (which may be one problem, or several unrelated problems):

- Oil leak under the engine (may be related?)
- Fuel gauge mysteriously flips to empty (with Low Fuel light), then kicks back to normal
- Occasional "freakouts", which consists of....
o Engine sputtering, getting ready to stall
o Dash lights dimming
o RPMs dropping
o Oil pressure dropping
These freakouts usually happen when idling, but I've also noticed it running rough even when driving at normal street speeds.

Some backstory....

We had recently noticed some odd behavior at high speeds (the tach was bouncing a bit, surging forward and then letting up). Check engine light came on at one point. Took it to Checker, and their diagnostic tool said it was a slipping transmission (there was also a code for the MAP sensor, but we hypothesized that the transmission was the *real* problem). Took it to the transmission place, and they fixed (if I recall correctly) the pump and the torque converter.

Got it back from the transmission place, drove it around, and it worked great (couldn't recreate the original problem) -- until I was pulling onto our street and it started acting rough. Check engine light came on. Took it to Checker again, and it was the MAP sensor code again.

So, today, I went ahead and replaced the MAP sensor. The actual sensor portion of the old one was covered in oil, and it looked like it was starting to disintegrate. Definitely needed to be replaced.

Took it for a test drive, and everything seemed to be awesome (engine running more efficiently, for one thing), until I was at a stop light and the engine started one of the freakouts described above. Check Engine light came on again. Argh.

Drove it over to Checker to get the codes again. They came up with...

P0108: "Manifold Absolute Pressure/Barometric Pressure Circuit High Input"

...the same code we were getting before, but this time there were two others...

P0101: "Mass or Volume Air Flow (MAF) Circuit Malfunction"
P0404: "Exhaust Gas Recirculation Circuit Range/Performance"

...so it sounds like it definitely wasn't as simple as replacing the MAP sensor (though that probably needed to be done anyway).

Now, since all this stuff happened right after we got it back from the shop, it's temping to assume that the transmission place messed something up, but I don't think that's the case because we've actually had these problems (fuel flip, freakouts, etc.) at various times in the past -- just not as much recently. They've been on-and-off for the past few years.

The reason I include the oil leak is that we had actually brought it in to the dealership a couple years ago to have them diagnose it. I don't remember their exact explanation, though I believe it included the words "manifold" and "cracked," and I recall they wanted a heap of money (which we didn't have) to fix it. I didn't really trust the guy I was talking too, though, so I don't know if that was accurate information, and we took the classic automotive strategy of ignoring it and hoping it would go away.

So, that's where we stand now -- after putting lots of money and time into it, the Blazer actually runs *worse* now than it has in the past several months. We don't have the cash to just take it to a mechanic and ask them to fix it, so I'm probably going to have to tackle it myself (if possible).

(Oh, and it's due for emissions testing at the end of the month. Of course.)

Any ideas??

Thanks!
James

Oil Leak: many possibilities. look at the remote oil filter/cooler lines, they leak all the time. If they are getting bad, replace them because if one lets go, you'll most likley damage your engine. Also take a look at you oil pan bolts etc.

Fuel Guage mystery: if the guage dances back and forth when you hit a certain level of gas in the tank, its usually your sending unit in the tank thats bad. Again this is a very common problem with these trucks.

Dimming/rpms dropping/oil pressure dropping is probably all interrelated. If its getting ready to stall many times, your rpms will drop, you'll defiently get dimming becasue your alternator is not being spun quick enough to produce proper voltage, and your oil pressure will also drop as it relates to the engine rpm too.

You mention your EGR, if the EGR is stuck open, it will run like crap and sputter and want to die all the time.

For your MAF. Take it off clean it with brake cleaner, not carb cleaner, but brake cleaner. Get it good and clean dry it up and reinstall it. Also another thing, slightly bend the connectors on the MAF a little bit, very slightly. This will give a good connection from the harness conector to the MAF.

Again EGR looks like it has to be cleaned. It sounds like its partially clogged/getting stuck. Give it a good cleaning and see what happens.

Reset your computer and see what happens.

Are you loosing any coolant? Do you have any coolant leaks? Usually if "intake" and "cracked" are in the same sentence, it usually has to do with the intake manifold gaskets leaking, as again, another common problem with these trucks.

Id say start with a good MAF cleaning, EGR cleaning, and see what happens.

Good Luck!