Have a 2006 caravan 3.8. Won't go over 3000 rpm. No codes.

Question edited for clarity. Please always quote DTC Codes in full. '129' is not the same as 'P0129'. Single numerical codes are usually computer communication codes.
Question moved to model category.

When you did all this work, did you disconnect the battery?
Did you reset the security system and engine immobilizer?
Is the anti-theft light flashing, flashing fast or on steady?

Help and videos

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Hi , could you supply the correct engine code and vin number ?
For the engine code (EKG) the firing order is 1-6-5-4-3-2
For the engine code (EGH) the firing order is 1-2-3-4-5-6

That looks to me like the rev limiter. I usually see that at 4,000 rpm but it seems like its working great. It should only limit like that in park or neutral. Does it also do that in drive? It shoul go to about six or seven thousand in drive when you out it to the floor.

When your driving or when in park?

If it wont go over in park this is normal. It is the rev limiter kicking in so that the engine will not self destruct.

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Is the check engine light on? Have you run a fault code test? Is the fuel pressure within specs under load? Is the exhaust system restricted and has excessive backpressure?

COULD HAVE FAULTY OIL PRESSURE SENDING UNIT.CHECK OIL PRESSURE SHOULD BE 25 - 80 PSI AT 3000 RPM. 30 - 80 PSI AT 3000 RPM.

Your engine is design to prevent it from red lining by accidently stepping on the gas while it is parked.

There are o2 sensors in the exhaust system either side of the converter. Look somewhat like spark plugs with wires going to them.

You say 3 rpm, do you mean 300 or 3000 ( I am guessing 3000)???

I do not believe any engine will run at 3 rpm.

Is this a manual trans, I assume so.

Test at the spark plug if you are getting current there with a cheap spark plug tester, if not, it could be the spark box. ( it used to be an ignition coil on older cars ) double check the computer for codes which may lead to a cam sensor not giving the PCM information.