Car losing power in upper rpm's/Bad mpg?

[Kraze]

Well ever since I got my car, it seems to die off pretty quickly anywhere above 5-5200 rpm. The acceleration definitely noticabley decreases, and I didn't think this was normal for it to be doing that, but I've always just dealt with it. Since then I've got an Xcal 2 tuned by torrie, but that didn't fix this "problem" though. I'm wondering what possible things could be causing this?

I've also heard about everybody getting upper 20 highway mpg, and I have never been able to get over 23-24. In the city it never gets above 13-14 either. This is all driving conservatively, proper inflated tires, properly maintained, so on and so forth. Any ideas, or should I just expect this?

My car is a '97 base with 108k miles on the clock. Since I acquired it about 7-8k miles ago I've changed the: oil (of course), pcv valve, transmission flushed and replace with mercon v, fuel filter, oil filter, spark plugs, air filter, and gave it a seafoam and techron treatment.

There's no DTC's. I've already done some datalogging with the Xcal, but I'll definitely do more if someone has a suggestion for something to data log.

 

[unity]

Do the basic first. Its like when ya go to the doctor and they check blood pressure and tell ya to say "ahhhhhhh".

You made no mention of a fuel filter replacement, have you?

I would also remove the tune and get it running right first.

1. Take it to Autozone for a code check, even if you get no CE light. ALso the tune can be hiding codes.

2. Vacuum check. Buy or barrow a gauge, they are cheap and worth keeping around in my opinion.

3. Fuel pressure check. The gauge kit costs a little but, but again its something worth having. Since its higher RPM and under load you may want to look at one you can use while driving, or cut and add hose extension as I have done.

4. At that milage, probably not a problem but the car is getting older so you never know. I wold check out the boots of the coils for cracks and such. You may be getting a slight mis-fire.

 

[98LSC32V]

The fuel pump maybe getting weak.

 

[lscmkviii]

o2's!