I have an 1987 Lariat 302 w/EFI. Some back ground on this truck. I bought it in April of 2011. The truck had sit for about 3 to 4 years. I cleaned the gas tanks out by hand, changed all fluids,tune up minus the distributor.I have replaced the TPS, Speed sensor,in line fuel filter(twice) both fuel pumps and filters,and had the transmission flushed.
When driving along and I go to aggressively accelerate the engine works had but I slow down slightly. I now am hearing a knocking as I let off the accelerator. This seems to be worst when the engine is hot. I had an OBD-1 but don't really know how to use it (other tan plugging it in and turning on the truck). I have trouble codes for the TPS, but the one in the truck is less than 5 months old. What else can I do. what else could be wrong. How do I diagnosis my problem.

 

i hope you dont have a bad rod, when i lost a rod bearing it did that for about a week, everytime i let off the gas it would start knocking, then it progressivley got worst until you could hear it all the time

 

any way to check the rods when you pull the valve covers? I tried to wiggle them around and they were all solid.

 

You're thinking pushrods, whole different story, a bent pushrod, loose rocker arm, etc will usually make a constant noise, that gets faster as the engine revs.
Does the motor make noise at idle, in or out of gear, or only when its moving on the road?
Is there oil in it?

 

connecting rod... Ahh... Make myself look like an idiot. Hahah
Well any way to check those?

 

The knock is only after I let off the gas of a hard acceleration, and it's only one of two knocks. When the engine is cool no problems. When the engine gets hot (an hour or so of driving) it starts to buck and shudder when I accelerate. And its getting worst each day

 

Oh and the engine make a wheezing noise in Idle. I'm 90% the wheezing is the water pump. When I first start it up and I accelerate I heard a strange honk type sound . It kinda sounds like a goose, but this goes away with in a minute and seems to have no relation to the acceleration problem.

I was thinking that the whole problem could be e-vap or transmission, but I really have no idea..I'm far from a mechanic

 

Thanks to everyone who has responded. Hopefully I don't sound like too much of an idiot