Hey guys, got a 97z with about 135k on the odometer. I have 4.10s out back so first gear is gone in a hurry but in the taller gears like 3rd and 4th I get a bobble in the power band in the upper RPM range , probably i would say between 3500 to 5500 (maybe more like only 4k-5500). I suspect possibly a bad opti but im not sure if it may just be the cap and rotor that need to be replaced. ALSO i have no clue how many miles these plugs/wires have on them either. I have had the car for about 20k miles now.

Steve

 

When you buy a used vehicle and don't have maintenance records, it's a good idea to assume NOTHING has been done. With that in mind, your place to start is a good tune up.

Plugs

Wires

Opti (not just cap and rotor since the bearing goes bad often)

Check ALL the wiring connected to the opti, icm and coil for bent pins or corrosion.

Have the misfire counters checked and cleared if nec.

Clean the MAF, throttle body, IAC and EGR valve and passage.

Just go ahead and change the TPS.

I highly urge you to have the injectors cleaned on the rail professionally or even better off the rail to have them flow matched.

Have the exhaust checked for back pressure. With 135k on the clock, chances are good the cats are restricted. Although on OBDII, there should be a cat efficiency DTC if so.

Have both the O2s(front 2) and temp sensor checked to be sure they are functioning properly.

Dave