My girlfriend has a 99 Blazer with a 4.3 and 137000 on the odometer. There seems to be several things going on at different times with it so bear with me.

She is getting an intermittent check engine light. It'll stay on for a while then go off. Usually when the engine is under load (uphill) And you can feel a slight loss in power when it comes on.

The trans seems to be shifting strangly. It'll upshift and downshift while maintaining the same speed. The trans was just serviced about 3000 miles ago and the fluid level is fine.

The past two days the truck has died out on her. Going up the road, the POOF, nothing. It starts right back up again and all is well. It doesn't do this if she lets the engine get to normal operating temp before driving.

The oil was just changed, and new plugs + fuel filter within the past 2 months.

Any help would be appreciated.

Thanks

 

When the check engine light is on, take it to an AutoZone and have them read the codes

That may give you an area of the car to take a look at, if not a specific thing to fix

 

I have a code reader, the problem is it comes on for a few minuted while she's driving and then goes back out. By the time I get to it it's long gone.

 

A complete tune up would help, but might not solve the problem.
Complete tune up is plugs, wires, cap, rotor, air filter, fuel filter, and pcv.
I would also pull the EGR and make sure it is functioning proberly.

Do you have a Haynes/Chilton manual for it?

The tranny is acting goofy becuase the engine isn't running properly. Your tranny is controlled by the computer, and the computer gets its info from the various sensors attached to the engine. It could be as simple as a stuck EGR, or vacuum leak, or a faulty reading from one of the sensors.

 

Solved one problem this morning. It died on her in the driveway. So I could actually see what was going on with that issue. Loose battery cable.

I'll try to take care of the other items mentioned this weekend.