1996 Toyota Camry Acceleration

My 1996 Toyota Camry LE has been acting erratically lately and it just started this behavior almost 2 weeks ago out of the blue. Upon start-up, the RPM stays below 1 and the car and motor shakes as if it's about to cut off but it doesn't. I cannot accelerate past about 40 mph unless I'm traveling downhill no matter how much I press the gas pedal. My father and I have taken off the maniforld and catalytic converter and punched holes in them both so that they could breath and dumped all the gunk which most people tell us is "platinum?" Out. We have changed the spark plugs which the car calls for 2 pronged spark plugs but I have had the car since February of 08' and the originals were only 1 pronged, but following the directions of the 1996 Toyota Camry LE guide we went on ahead and installed 2 pronged spark plugs. The only thing we think is wrong now is either we need a new manifold and catalytic converter or we need new spark plug wires because when we pulled the wires off to change the spark plugs the clips that were suppose to stay on the wires stayed on the spark plugs and we had to pull them off and then we sort of took vice grip pliers and put them back on the wires to clip onto the new spark plugs. We are not sure if that damaged the connection or not PLUS it kind of stripped the wires. Also, inside the car does not show that it's going hot but outside on the manifold it smokes and there's a strong smell of oil. Please give me your opinion on what you think the problem is because I am in need of this car bad. Thank you.