If it idles fine without any help, the pushrods are likely fine.

 

I thought I had done something wrong after I installed my cam because my truck wouldn't stay running after I got everything put back together. Turned out I just needed a tune. My truck kind of seems to do what your talking about but mine does it around 10-15 MPH like if I BARELY have my foot on the gas it kinda acts like it wants to just take off if you can understand what I mean lol. I would highly recommend that if you're gonna tear back into your truck to go ahead and buy a timing set and whatever else you might want to replace if you plan on keeping it, that's what I am doing. I got a brand new water pump, timing set, upper and lower radiator hose, etc.

 

If you want an inductive timing gun, I have a like new one here. However, since there is no timing mark on the cover or engine, it won't help.

Follow those pics in that cam swap how to thread I did and you will be fine. Nothing wrong with setting the timing chain and rotating the engine a couple times to check and recheck