I have an intermittent surging issue while at low rpm cruising highway speed. Now it will sometimes do it while idling in gear at a stop light. I have changed the tps/iac and the egr sensors. Today the truck started throwing an air bag code.
Today I unplugged the mass air sensor,the tps and the iac while the truck was running and it had no effect what so ever, the truck will even rev and accelerate normally. I am at a loss as to what is going on.

 

How many miles?

 

The truck has over 300,00 miles on it.
The engine has been replaced at 206,832 and the transmission was rebuilt in 2011 at 145,600.
The transmission fluid and filter were changed at 202,100.
I have replaced the sensor's over the last couple of month's as I am trying to figure the surging issue out.
The coil pack,spark plugs and plug wires have all been replaced.
The surging has been getting slowly worse over time, but is totally intermittent.
Sometimes it doesn't happen for days, then it will happen 3 or more times while I am driving.
I drive 52 miles one way each day to and from work and it doesn't do it everyday.

 

Any OBD2 codes?

 

No obd2 codes, but today it threw an airbag code for the 1st time.
I drove about thirty miles today and it surged 4 or 5 times on the way there.
It surged once on the way back.
Its completely random, I can't consistently make it surge so that I can figure it out.
It usually surges at low rpm highway cruising speeds, but it has done it sitting at a red-light a couple of times this week.

 

Check and if need be, replace your intake manifold isolator bolts with the new style ones with the green seals.

Also, check your EGR passages/ports while you are in there to see if there is any build up. If so, clean it.

 

I don't think the 98 had those isolator bolts. However, you may have gasket issues but it should be throwing lean codes if that were the case. You may have dirty injectors, put some Techron in in the gas.

 

Thank you everyone for the advice and input.
Sunday while i was driving with my scanner hooked up it finally threw a code for the camshaft position sensor.
I took it off and the metal insert had come loose inside the sensor.
I installed a new sensor and cleared the code.
I will scan the truck when i get home Monday night and see if any other codes pop up.
I drove 56 miles this morning and no surging, so i am hopeful that the cps was the culprit.

 

Excellent! Congrats!

 

Perfect news!! Glad you got it fixed!