1999 Ford F-150 engine is backfiring after tuneup

1999 FORD F-150
200,000 MILES • 4.6L • 6 CYL • RWD • AUTOMATIC
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DAMIANBEVERLY
  • MEMBER
  • 1 POST
I replaced my upper manifold gasket due to a vacuum leak. I also replaced plugs and wires. Cleaned the throttle body. Well after putting everything back together I cranked the motor. The vehicle runs great in park and neutral. As soon as it is put into drive the motor bogs itself down, idles extremely rough and backfires. I have know idea where to start on looking for the problem. What would cause this to happen after doing the work that was preformed?
Sep 6, 2015 at 7:48 PM
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RIVSHERIFF
  • MEMBER
  • 4 POSTS
Did you put spark plug wires in correct firing order?
Sep 6, 2015 at 8:08 PM
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RIVSHERIFF
  • MEMBER
  • 4 POSTS
Also everything torqued to correct specs, did you take off any connectors?check all that you think you may have touched
Sep 6, 2015 at 8:10 PM
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HMAC300
  • ✓ASE Certified Mechanic
  • 48,601 POSTS
  • ASE Certified Mechanic
recheck your work then scan for codes and check fuel pressure with a gauge auto parts rent it. check for vacuum hoses off broken/etc.
Sep 7, 2015 at 6:41 AM
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