I have a problem when I try to accelerate, the engine bogs down like it is not getting enough gas or something. If I slowly depress the pedal the engine does speed up but when put under load, it bogs down again. I have been fighting this on and off for a few weeks now. I had initially thought it was bad gas so when I worked through a tank or two it seemed to return to normal for a time. However it has returned. I added SeaFoam to the tank but it has not resolved the problem.

 

I can find no vacuum leaks and the car idles normal, no skipping or misfiring. I can't imagine it is bad gas at this point. 

 

I looked on the formums before posting and did find another person with a similar issue in a 89 wagon and his was a coil issue. Could this be what is happening with mine? 

Try changing the fuel filter cheap and easy

Can't hurt

Edited January 7, 20179 yr by ferp420

Fuel filter.

 

Also, possible partially blocked exhaust.  Test by loosening the 4 exhaust manifold nuts, to get a 1/2" gap.  It will be loud, but it will run.  If the exhaust is ok, it will have no other effect, except possibly the CEL.  If it runs great under load with the exhaust off, then probably one of the cats is clogged.

I would suspect ignition components first-plugs,wires etc.

 

Well worth checking how plugged the fuel filter is too.

Check your front catalytic converter. I had a similar problem awhile back and replacing the cat fixed the problem.

I had recently changed the fuel filter so I know that is ok and the exhaust was replaced last year.

I would definatley put a set of denso platinum plugs in it dont go iridium think they burn to hot for older motors.

Guessing wildly Air filter   cloged or failing fuel pump cloged fuel tank pick up did they replace the o2 sensor when they did the exhaust is there excessive blow by how's the compression bad ground maybe if it was ignition related I would expect a lot of back fireing and piping also ruff running and idleing

I would guess a plugged air filter - really bad silty sand.. or more probably a plugged catalytic converter.  Let us know when you find out.

Change the O2 sensor on the exhaust.  They go bad every couple of years and screw up the fuel air mixture when cold.

I had a similar problem when i was building mine. If you have a stick air air cleaner there is a thermo valve  that opens up once it is warm and it creates a huge vacuum leak, plugged it off and no more problems. It would run and idle great when cold but once it warmed up i had the same issues you are dealing with. Just a suggestion since i chased all the other issues down ... filters gas etc. Also in the carb the orifice that squirts the gas into the carb is extremely small. It does not take muck to clog it up. HAd to use a wire from a wire wheel brush to clean it out. 

When you refilled your tank with new gas did you go to a different station or stay with the same station ?  Bad gas can be a problem with the source.  Your comment that it got better for a while indicates you might be buying from a cheap source. 

 

I had this type of problem many years ago.  Changed purchase location and problem never returned.  Now I only buy from shell, mobile or chevron.

 

Also make sure you are not getting anything higher than E10 ethanol content with good octane levels.  These old engines don't like cheapo gas.

Hitachi carb?

If carbed it might be accelerator pump perhaps

I removed the air filter assembly, which is a pain cause there are some many vacuum lines and hoses. But, once I got it off, it made the work so much easier.

 

After I got that out of the way, I had to plug up a few of the open lines cause they were causing vacuum leaks and the car would not run. Finally I got the motor running and it ran great, like it should. I wasn't crazy about driving it without the air filter on but I had to test it. The car drove exactly like it should. The idle was great and the acceleration was back, like it should be, no hesitation.

 

I put the air filter assembly back on and left the tubes plugged and disconnected. Went for another run and it was perfect. My car is back to life once again!

 

I may go back in the warmer weather and determine which hose was the problem, but for now, I don't care, it's running!

Vacuum leak, then.