I'm not a mechanic (but I'm great with electronics) and need help getting my 380,000-mile Blazer off it's crutches.

-- Thanks in Advance --


Problem...

1990 S-10 4wd 4.3L

Going uphill, loses about 40% of its power after about 10 seconds, then about 10 seconds later, usually backfires out the exhaust (I think) one time.


What I've Done So Far...

Replaced most vacuum lines.

Checked most electrical connections.

Has relatively new catalytic converter.

Took air filter off (for a test drive only), and it seems to run a little better and looses less power and backfires quite a bit less.

I checked codes. There are no codes set. I just got 12-12-12.


What I Suspect... (but I'm a novice)

Done a lot of research.

The only suspicion that I have is this.

I had one of those oil-based air filters on for a while to try to get more performance and save some money (in the long run). A few months after, this problem began gradually.

It slowly became worse and worse, but I never made any connection to the oil-based air filter.

I just read that some people had air-flow sensors in their throttle bodies go bad because they thought the oil from the air filter messed it up.

This truck uses a MAP sensor. Could that get messed up with oil from an oil-based air filter?

I'm not sure what else to look at, so I'm open to any suggestions.

Thanks!