Car will not go above 2900 rpm s

speed sensor

Attached is a drawing of 6 cyl 4.2L engine, crankshaft position sensor is item #709 on driver's side of engine toward rear.

THIS IS NOT A PROBLEM.

May need to replace the stepper motor behind the tach. Although, sometimes the ignition switch is the culprit. Has the transmission fluid and filter been changed?

Set all new plugs to 25 thou ,if s/hand 22 thou and also check the HT Leads for shorting out .
Ron

The air filter should be under the hood near the grill .

Typically it is a 255/65R/17 or 255/70R/17

On 05+ Trail Blazer, the fuel filter is integral with the fuel pump inside of the fuel tank. It is a non-serviceable part. On 02-04s, the filter is on the drivers side frame rail at about the B-pillar. If your trail Blazer is a late 04 which means that it was build close to the 05 Trail Blazer, you may have a non serviceable fuel filter. Good luck and check under your Trail Blazer or look at your manufactured date sticker on the door which would help you indicate if your 04 is a early Trail Blazer and you'll have the fuel filter on the inside frame rail under the driver's door.

if you cant see one then just remove bottom hose but be aware of hot water !

#1 cylinder is the first one on the front of the engine on the drivers side. the reason for your misfire is most likely either a bad plug, bad plug wire, the coil pack or all of the above