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Just bought an '86 Cabriolet. 350K Kms. previous owner let it sit for maybe 18 months with fuel in the tank. I put in about 30 litres of 87 octane. Engine runs happily until there's any sort of load other than flat ground. Then it misses and loses power. A sample of the fuel was stinky. Have changed spark plugs, and wires. the fuel distributor has had the sliding valve cleaned. Will remove most of the gasoline and put in some injector cleaner, but I have my suspicions about the fuel distributor system.
 

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Just bought an '86 Cabriolet. 350K Kms. previous owner let it sit for maybe 18 months with fuel in the tank. I put in about 30 litres of 87 octane. Engine runs happily until there's any sort of load other than flat ground. Then it misses and loses power. A sample of the fuel was stinky. Have changed spark plugs, and wires. the fuel distributor has had the sliding valve cleaned. Will remove most of the gasoline and put in some injector cleaner, but I have my suspicions about the fuel distributor system.
I would be running SeaFoam Engine Treatment or MMO Marvel Mystery Oil in the Gas Tank as it cleans Varnish out.
Runs good until load (Is there a whine when this happens from the right side rear wheel arch?) The 86 has 2 fuel pumps, one in-tank and one in the main line.
Which is why I asked about the whine.

Seafoam or MMO is very helpful, I would look for Vacuum leaks, possibly the Throttle body bypass screws o-ring, is hard and leaking air it is on the back of the throttle body near the firewall if it turns by finger tip, it is bad, count the turns to remove it, replace the o-ring and wrap the Threads of the Screw threads only with yellow teflon tape.

I would first suspect timing as it runs. After statically setting the timing, and adjusting to 6btdc on a timing light, then you have to set the Duty cycle. www.cabby-info.com has good links to how-to's on setting this.

I have also seen internal collapsed mufflers cause issues with the running of a car flat out. Had one that idled great but under load it would choke and puke.
I have also see that your plugs if they aren't NGK can cause issues as well s the HV leads from the cap to the plugs.

Since you said it runs until load I wouldn't suspect the fuel diz yet, but concentrate on Idle, timing, Duty Cycle, and vacuum leaks.

If you haven't replaced the main ground from the Battery-frame, and frame to engine grounds the electrics can cause wonky things...
It is the fist mod that I do to a new to me car.
 

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Oh, welcome to the ROC, I approved the thread, and moved it to the OLDER Rabbit forum where you will get answers faster.
 
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