I have a 89 b250, I did a smog delete, installed some Moog 7272 coil springs but other then that its stock 318 tbi.
I need help because my van started having this real bad hesitation problem when I hit the gas, when the van is cold its like a bucking bronco it does get better after driving a while but still does it.
I have replaced the following already: tps & map sensors, cap & rotor, fuel pump-strainer-fuel lines & fuel filter.
I am at a loss.......maybe a vacume leak?????? but this must have happened to someone else????

 

Air filter, sparkplugs and wires should be done too. This is a common problem when a tune-up is due.
Steve

 

Detail smog delete. If you removed 02 sensor, there is your answer.

Otherwise, whenever I have had hesitation on my '89, it has been spark plug wires.

Also it is possible that you have a bad ECM connector, and this might not set a computer code or flash the check engine light.

Turn key to on, not start, wiggle connectors at engine computer, and see if you hear relays click on and off or the idle speed motor moving when you wiggle the connector.

 

I know about 3% of bugger all, so please excuse the ignorance but my intentions are to help. I have indeed suffered similar sudden behaviour like you describe and the cause was a damaged fuel cap. The air hole was clogged and caused a vacuum in the fuel line/emission dohickies. A quick poke around and clean up and no more stuttering. Hope this is relevant and helps.

 

I know about 3% of bugger all, so please excuse the ignorance but my intentions are to help. I have indeed suffered similar sudden behaviour like you describe and the cause was a damaged fuel cap. The air hole was clogged and caused a vacuum in the fuel line/emission dohickies. A quick poke around and clean up and no more stuttering. Hope this is relevant and helps.

 

My jeep did the same thing. Was the timing chain. Does yours backfire?

 

Plugs, wires and coil need to be done. You only did a partial tuneup.

 

check