Got a question for everyone. I have a 1993 Ford F-150 XLT ext cab. 5.0 aod. when i put it in OD (no push button) and im cruising on flat ground with no accelerating seems smooth, but when i accelerate a little it start bucking terribly. I have to down shift to D. It has 156,000 miles, I have put a cold air filter on it, chipped it, MSD blaster coil, newer plugs, wires, cap and rotor. It did the same thing before the tuneup. What do you think could be the problem. rear tires are 31-10.5/15.

 

Check the air injection system for leaks, a crack or rust hole anywhere in this system upstream of the O2 sensor will cause a severe lean condition. I would suspect this is accompanied but detonation(pinging) as well and your chip is probably agrivating the situation.

 

Yea my air tube to the cat is plugged and not used

 

That's the one part that doesn't matter you could leave it wide open if you like, it's all the plumbing between the air pump and the back of the motor that matters.

 

Ill look over it all this week to find what could be the culprit. would that also cause my Mileage to suck major ***..... Im getting 10-13 mpg.