So I got a 97 ford f250 hd and if in drive and start goin till I get to 30mph it starts jumping in rpm like it done know what gear it should go in. But if I change my gears 1st 2nd then drive it doesn't do the chugging. I've changed several sensors please help I'm clueless..

 

Did you notice what the speedometer needle is doing as this happens ?

Just curious ,when was the fuel filter last changed?

Would you describe the symptoms as breaking down under load?
Did you check the EGR valve for being full of carbon?
When was the last tune up ?

 

I've not noticed anything different in the speed needle as for it will still try in climb to the speed I get it to. But I have already replaced the fuel filter, map sensor, vss on the rear axle. Now as for the egr I've not done that yet but I will tomarrow wast there be one in stock at one of the auto stores. Well i wouldn't say it's breaking down underload but it just seems like it doesn't know what gear to go in at the speed unless I shift it manually on the column. So would that be where you start at is egr valve. Cause I got 2 more sensors to throw on in the morning one being the output sensor that goes on the trans and the range selector sensor.

 

I've not noticed anything different in the speed needle as for it will still try in climb to the speed I get it to. But I have already replaced the fuel filter, map sensor, vss on the rear axle. Now as for the egr I've not done that yet but I will tomarrow wast there be one in stock at one of the auto stores. Well i wouldn't say it's breaking down underload but it just seems like it doesn't know what gear to go in at the speed unless I shift it manually on the column. So would that be where you start at is egr valve. Cause I got 2 more sensors to throw on in the morning one being the output sensor that goes on the trans and the range selector sensor.

 

We try to determine if a part is malfunctioning before replacing it.
Throwing parts at a problem can get expensive and disappointing.
If you look at all the $$ spent replacing good parts, that $$ could cover a good shop performing a thorough diagnosis.and pinning down the real cause.

 

You are correct.. so where would you start?

 

What we try is to look at the data stream info and look for any codes.

Based on what we see there, determines what and where we go next.

Just like the doctor looks at a patients blood work, a good tech looks at the data stream info and goes from there.

A capable scan tool is required to access the right info and that is why without that capability a good shop is suggested.
The days of turning a screw or replacing a particular part is pretty much out of the picture.
Vehicles these days require some special tools and training to properly diagnose.

 

Well said @hanky !!

 

To our Diesel Specialist , bismic, thank you for the kind words !!.

 

So I put it on a scanner and it wouldn't make connection so maybe I should just resale the truck and make it someone else problem.. as for I'd hate to do that.