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Hello. Just got my 78 a couple of weeks ago. Had few problems I have been fixing with help from the site like horns, shifter bushing, gauges, wipers, etc but have one I haven’t seen before. 
 

Car runs fine, maybe a tiny bit rough when cold but smooth warm and a slight trouble hot starting (couple of extra cranks and a bunch of pedal) but neither are too bad. Car idles fine and revs all the way through. Sometimes when I push it hard, there is a slight backfire from the exhaust. 
 

The problem I have is when I reach cruising speed and begin to feather the gas pedal to maintain speed. The car will cut out like the fuel has been cut or the throttle has snapped shut. first time I thought the engine had died completely. As soon I push on the pedal it kicks right back in and drives normal. I don’t have to give it much gas to get it on again. It seems to happen in any gear and any speed. It’s that fine tipping point when I am just barely on the gas. The cut out seems more pronounced than when you just let off the pedal to decelerate. Makes you kinda lean forward from the quicker slow down. 

 

I already started adapting to it by reaching my speed and then it cuts out. I will let the speed drop off a few mph then slowly speed back up and when I ease off it cuts out again and I do it over. Back and forth. it always comes right back when I push through it though. 
 

I thought the throttle linkage might have too much play in it and was snapping back when I eased off but the play doesn’t seem too much.. Maybe there is a dead spot that causes the computer to lose signal completely and cut out at that exact throttle position?

 

I see there are a bunch of adjustments to things like the TPS but I wanted to ask before I started monkeying about with things. I tried to search but have no idea how to word my problem much less find it. 
 

Does anyone have a guess? 
 


Also a free pic just because

 

456EBA4E-A4D0-4743-96C0-BB581A7E9801.jpeg

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Take off your afm boot that runs to the throttle body.  Look at the throttle plate area.  See if you are gummed up around the throttle plate.  It gums up over time from the crank case and purge valves, that recirculate blow by gasses.  It will not allow enough air flow when the plate is closed.  Clean it up the throttle plate and area around it with carb cleaner.  Then re-install the boot and see if solved your issue.

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