2001 Nissan Frontier shudders when put in gear

2001 Nissan Frontier 3.3L v6 140,000 miles



Starts fine and runs fine most of the time. For the last month or so, after starting (starts fine), put it into gear, reverse or drive, and it shudders or bucks. If I let it warm up 2 - 3 minutesin park or neutral, it goes away and runs fine from there on out. It doesn?t do it all the time. Only when it hasn?t been run in a couple of days. I ride my bike to work a couple of days per week and every time the truck has sat for two days without running, this happens.



Recently had the transmission fluid flushed and changed. (fluid level checked and ok)

New air filter.

New fuel filter.

Fuel injector cleaner.



Any ideas what might be going on?



Thanks,

Greg

Bump, any ideas?

A WAG: a leaking fuel injector is dumping gas into the intake when the tuck sits for any length of time.

It cranks and idles fine. Only when I put it in gear does it act up. Do you still think fuel injector?

Thanks, Greg